Position sensor

ABSTRACT

A position sensor device determines a position of a reciprocating object and includes, (a) at least one magnetically encoded region fixed on a reciprocating object, (b) at least one magnetic field detector, and (c) a position determining unit. The magnetic field detector is adapted to detect a signal generated by the magnetically encoded region when the magnetically encoded region reciprocating with the reciprocating object passes a surrounding area of the magnetically encoded region. The position determining unit is adapted to determine a position of a reciprocating object based on the detected magnetic signal.

FIELD OF THE INVENTION

The present invention relates to a position sensor device, a positionsensor array, a concrete processing apparatus and a method fordetermining a position of a reciprocating object.

DESCRIPTION OF THE RELATED ART

For many applications, it is desirable to accurately measure theposition of a moving object. For instance, it is highly advantageous toknow the position of a reciprocating object to accurately control thereciprocation in an efficient manner.

According to the prior art, an optical marker can be provided on areciprocating object, and an optical measurement can be performed toestimate the position of the optical marker and thus a position of thereciprocating object. However, under critical circumstances andconditions such as a dirty environment, the optical marker may becovered by a layer of dirt and may become “invisible” for an opticaldetecting means.

Further, in case that the reciprocating object is located in a dirtyenvironment, an optical marker can be abrased by friction between thereciprocating object and dirt particles.

Such a scenario of critical conditions is present, for instance, in thecase of a concrete processing apparatus in which a reciprocating shaftmixes concrete and in which the position of the reciprocating shaft orwork cylinder is desired to known to efficiently control thereciprocation cycle.

Alternatively, a mechanical marker, such as an engraving, can be used asa marker to detect the position or velocity of a reciprocating object.However, such an engraving structure may be filled or covered with dirtand is thus not appropriate to be implemented under critical and dirtyconditions. A mechanical marker (engravings) may also present achallenge to maintain pneumatic or hydraulic sealing.

SUMMARY OF THE INVENTION

It is an object of the present invention to enable an accurate positiondetection of a reciprocating object capable of being used under criticalconditions like a dirty environment.

This object may be achieved by providing a position sensor device, aposition sensor array, a concrete processing apparatus and a method fordetermining a position of a reciprocating object according to theindependent claims.

According to an exemplary embodiment of the invention, a position sensordevice for determining a position of a reciprocating object is provided,comprising at least one magnetically encoded region fixed on areciprocating object, at least one magnetic field detector, and aposition determining unit. The magnetic field detector is adapted todetect a signal generated by the magnetically encoded region when themagnetically encoded region reciprocating with the reciprocating objectpasses a surrounding area of the magnetic field detector. The positiondetermining unit is adapted to determine a position of a reciprocatingobject based on the detected magnetic signal.

Further, a position sensor array is provided according to an exemplaryembodiment of the invention, comprising a reciprocating object, and aposition sensor device having the above-mentioned features fordetermining a position of the reciprocating object.

Moreover, a concrete processing apparatus is provided according toanother exemplary embodiment of the invention, comprising a concreteprocessing chamber, a reciprocating shaft arranged in the concreteprocessing chamber adapted to reciprocate to mix concrete, and aposition sensor device having the above-mentioned features adapted todetermine a position of the reciprocating shaft.

Beyond this, a method for determining a position of a reciprocatingobject is provided according to an exemplary embodiment of theinvention, comprising the steps of detecting a signal by a magneticfield detector, the signal being generated by a magnetically encodedregion fixed on a reciprocating object when the magnetically encodedregion reciprocating with the reciprocating object passes a surroundingarea of the magnetic field detector, and determining a position of areciprocating object based on the detected signal.

One idea of the invention may be seen in the aspect to enable accurateposition detection of a reciprocating object, such as a reciprocatingworking cylinder of a concrete (or cement) processing apparatus, byproviding one or more magnetically encoded regions on the reciprocatingobject. When the reciprocating object reciprocates, the magneticallyencoded region passes—from time to time—an area of sensitivity/asufficient close vicinity of a magnetic field detector so that a counterelectromotive force may be generated in a magnetic coil as a magneticfield detector by which the presence of the magnetically encoded regioncan be detected. Since the position of the magnetically encoded regionson the reciprocating object is known or can be predetermined, thedetermining unit can derive from the detected signal the actual positionof the reciprocating object. To determine the position of thereciprocating object from the detected signal, correlation informationcan be taken into account. Such correlation information can bepre-stored in a memory device coupled with the position determining unitand may correlate the presence of a particular signal of a particularmagnetically encoded region with a corresponding position of the shaft.In other words, correlation information correlates a detected(electrical) signal with a position of the object.

“Position” in the context of this description particularly means theinformation that a particular region or point of the reciprocatingobject is located at a determined position at a particular point oftime.

The fact that the magnetically encoded region is fixed on thereciprocating object means that it may be integrated as a part of theobject or alternatively may be attached as an external element to thesurface of the object.

Particularly, one or more magnetically encoded regions can be formed ondifferent portions of a hydraulic work cylinder, wherein each ofmagnetic field detector(s) senses a detecting signal each time amagnetically encoded region traverses a sphere of sensitivity of themagnetic field detector. Thus, the position, the velocity, theacceleration, and so on, of the working cylinder can be estimated withhigh accuracy, wherein this information can be used to drive thecylinder in a controlled manner to optimize its function.

Since the detection principle of the invention is contactless, thedetection is not disturbed by friction effects and does not require adirt-free environment. Thus, the invention particularly mayadvantageously be applied in technical fields in which a dirtyenvironment may occur, for instance as a position detecting apparatusfor a reciprocating shaft in a concrete processing apparatus, in thefield of oil boring, and in the field of mining.

Further, the magnetic position detecting principle of the invention canbe manufactured with low effort, is easy to handle and can be applied toany existing shaft by magnetizing a part of the shaft using a methodwhich will described in detail below (PCME, “Pulse-Current-ModulatedEncoding”). For instance, many industrial steels used for shafts of anengine or a work cylinder can be magnetized to form a magneticallyencoded region of the invention. The detection principle of theinvention is very sensitive and provides a good signal to noise ratio.

The invention can be applied to reciprocating objects like areciprocating shaft having a full scale measurement range for instancein the range of 1 millimetre to 1 meter, but which may be less than 1millimetre, or which may be as much as 1 (or more) meters.

The invention particularly allows to identify certain (absolute)positions (or fix points) on a reciprocating object, like the positionwhere a pump or generator has to be shut off (on-off function). Thisinvention can also be used to make a precise measurement at a specificrange on a reciprocating object (defining a linear position on anobject).

While different types of linear positioning sensors (the concept ofwhich differ fundamentally from the concept of the invention) exist inlarge quantities and that for a relative long time, this particularinvention is particularly designed to function under harsh and abrasiveconditions where most other technologies will fail.

An aspect of a PCME based linear position sensing technology accordingto an exemplary embodiment of the invention is that the magnetic pick-updevice may be very small and therefore can be easily placed in smallspaces, like inside of a sealing chamber in a pneumatic or hydraulicdevice.

Another benefit is that the magnetic field emanating from the permanentmagnetic markers is relatively small and therefore will not attractmetallic particles. A typical magnetic proximity sensor (like anautomotive wheel-speed sensor) uses very strong magnetic field tofunction reliable. Therefore ferromagnetic particles will stick on thesurface of such sensors which is why they cannot be used in dirtyenvironments.

The technology of the invention may be also used, in the frame of aconcrete processing apparatus, to control the hydraulic cylinderposition of the crane arm that carries the mixed and still liquidconcrete mass through a long and flexible pipe to a specific location ata building site.

The hydraulic cylinders need to be extended or contracted so that theheight and position of the crane arm can be changed. The PCME magneticmarkers are appropriate to identify the exact position at the cylinderand to detect vibrations or oscillations that are caused by the concretepump and the pulsing semi-liquid mass in the flexible pipe.

When the crane arm is pulsing/vibrating to much then the pump has tochange its operation to prevent a problem (crane arm is moving outsideof the acceptable position tolerance).

Referring to the dependent claims, further exemplary embodiments of theinvention will be described in the following.

In the following, exemplary embodiments of the position sensor devicewill be described. However, these embodiments also apply for theposition sensor array, the concrete processing apparatus and the methodfor determining a position of a reciprocating object.

The at least one magnetically encoded region of the position sensordevice may be a permanent magnetic region. The term “permanent magneticregion” refers to a magnetized material which has a remainingmagnetization also in the absence of an external magnetic field. Thus,“permanent magnetic materials include ferromagnetic materials,ferrimagnetic materials, or the like. The material of such a magneticregion may be a 3d-ferromagnetic material like iron, nickel or cobalt,or may be a rare earth material (4f-magnetism).

The at least one magnetically encoded region may be a longitudinallymagnetized region of the reciprocating object. Thus, the magnetizingdirection of the magnetically encoded region may be oriented along thereciprocating direction of the reciprocating object. A method ofmanufacturing such a longitudinally magnetized region is disclosed, in adifferent context, in WO 02/063262 A1, and uses a separate magnetizingcoil.

Alternatively, the at least one magnetically encoded region may be acircumferentially magnetized region of the reciprocating object. Such acircumferentially magnetized region may particularly be adapted suchthat the at least one magnetically encoded region is formed by a firstmagnetic flow region oriented in a first direction and by a secondmagnetic flow region oriented in a second direction, wherein the firstdirection is opposite to the second direction.

Thus, the magnetically encoded region may be realized as two hollowcylinder-like structures which are oriented concentrically, wherein themagnetizing directions of the two concentrically arranged magnetic flowregions are for instance essentially perpendicular to one another. Sucha magnetic structure can be manufactured by the PCME method describedbelow in detail, i.e. by directly applying a magnetizing electricalcurrent to the reciprocating object made of a magnetizable material. Toproduce the two opposing magnetizing flow portions, current pulses canbe applied to the shaft.

Referring to the described embodiment, in a cross-sectional view of thereciprocating object, there may be a first (circular) magnetic flowhaving the first direction and a first radius and the second (circular)magnetic flow having the second direction and a second radius, whereinthe first radius is larger than the second radius.

Alternatively, the at least one magnetically encoded region may be a(separate) magnetic element attached to the surface of the reciprocatingobject. Thus, an external element can be attached to the surface of thereciprocating object in order to form a magnetically encoded region.Such a magnetic element can be attached to the reciprocating object byadhered it (e.g. using glue), or may alternatively be fixed on thereciprocating shaft using the magnetic forces of the magnetic element.

Instead of attaching a magnetic object to the surface of thereciprocating object, it is also possible to use materials withdifferent magnetic properties (one material has a higher, and the othera lower permeability, for example). The magnetic object can be attachedfrom the outside of the shaft/cylinder or can be placed inside of thecylinder.

When using materials of different permeabilities, then an additionalmagnetic encoding of the shaft or cylinder is no longer necessary. Anexternal magnetic source can be used (in conjunction with the magneticpick-up device) to detect when the magnetic flux is changing as aconsequence of the moving shaft.

Any of the magnetic field detectors may comprise a coil having a coilaxis oriented essentially parallel to a reciprocating direction of thereciprocating object. Further, any of the magnetic field detectors maybe realized by a coil having a coil axis oriented essentiallyperpendicular to a reciprocating direction of the reciprocating object.A coil being oriented with any other angle between coil axis andreciprocating direction is possible and falls under the scope of theinvention. Alternatively to a coil in which the moving magneticallyencoded region may induce an induction voltage by modulating themagnetic flow through the coil, a Hall-effect probe may be used asmagnetic field detector making use of the Hall effect. Alternatively, aGiant Magnetic Resonance magnetic field sensor or a Magnetic Resonancemagnetic field sensor may be used as a magnetic field detector. However,any other magnetic field detector may be used to detect the presence orabsence of one of the magnetically encoded regions in a sufficient closevicinity to the respective magnetic field detector.

A plurality of magnetically encoded regions may be fixed on thereciprocating object. By providing a plurality of magnetically encodedregions, a number of fixed points on the reciprocating shaft are definedwhich may be detected separately so that the number of detection signalsis increased. Consequently, the sensitivity and the accuracy of theposition detection may be improved.

The plurality of magnetically encoded regions may be arranged on thereciprocating object at constant distances from one another. Thus, eachtime one of the magnetically encoded regions passes one of the magneticfield detectors, the reciprocating object has moved by a distance whichequals the distance between the magnetically encoded regions. Thus, theposition of the reciprocating shaft can be estimated in a time-dependentmanner with high accuracy.

Alternatively, the plurality of magnetically encoded regions may bearranged on the reciprocating object at different distances from oneanother. For instance, the different distances may be selectively basedon a linear function, on a logarithmic function or by a power function(for instance a power of two or of three). Thus, the time between thedetection of subsequent signals by one of the magnetic field detectorsfollows the mathematical function according to which the magneticencoding regions of the invention are separated from one another. Thisallows a unique assignment of the present position of the reciprocatingobject.

Such a mathematical function can be a positive (increasing) function ora negative (decreasing) function, meaning that the spacing can becomelarger from one to the next magnetic marker, or it can become smallerfrom one to the next.

The plurality of magnetically encoded regions may be arranged on thereciprocating object with constant dimensions. A constant dimension(e.g. constant width, constant thickness, etc.) yields signals of aconstant length in time as detected by any of the magnetic fielddetectors. However, in a scenario in which the reciprocating objectreciprocates with a non-constant velocity, the length of the signalswill change, so that velocity and acceleration information can bedetermined from the length of the signal in time.

Alternatively, the plurality of magnetically encoded regions may bearranged on the reciprocating object with different dimensions. This,similar to the case of providing the magnetically encoded regions atdifferent distances from one another, allows a unique assignment of themagnetically encoded region which presently passes one of the magneticfield detectors.

Thus, the magnetic markers can be either all of the same physicaldimensions (same width) or they can be of different dimensions (likebecoming larger one-after-each-other). In the same way the physicaldimensions of the markers can be changed, so can be their signalstrength. For example: The markers are all of the same physicaldimensions and they are all placed one-after-each-other with the samespacing to each other. The difference from one marker to the next isthat the signal amplitude (generated by the permanently stored magneticfield, inside the marker) is increasing from one marker to the next.

Different magnetically encoded regions may be provided made of differentmagnetic materials, and/or may be provided with different values ofmagnetization. According to this embodiment, the amplitude or strengthof the individual detection signals are different for each of themagnetically encoded regions so that a unique assignment of a detectionsignal to one of the magnetically encoded regions, being the origin forsuch a signal, can be carried out.

The position sensor device according to the invention may comprise aplurality of magnetic field detectors. This further allows to refine thedetection performance.

The plurality of magnetic field detectors may be arranged along thereciprocating object at constant distances from one another.

Alternatively, the plurality of magnetic field detectors may be arrangedalong the reciprocating object at different distances from another.

The different distances may be selected based on a linear function, alogarithmic function or a power function.

Such a mathematical function can be a positive (increasing) function ora negative (decreasing) function, meaning that the spacing can becomelarger from one to the next detector, or it can become smaller from oneto the next.

The position sensor device according to the invention may comprise aplurality of magnetically encoded regions fixed on the reciprocatingobject and may comprise a plurality of magnetic field detectors.

The arrangement of the plurality of magnetically encoded regions alongthe reciprocating object may correspond to the arrangement of theplurality of magnetic field detectors. In other words, the arrangementof the magnetic encoded regions may be symmetrical and may thuscorrespond to the arrangement of the magnetic field detectors. In otherwords, in a reference position of the reciprocating object, a centralaxis of each of the magnetic field detectors may correspond to a centralaxis of a corresponding one of the magnetically encoded regions.

Alternatively, at least a part of the plurality of magnetic fielddetectors may be arranged displaced from an arrangement of acorresponding one of the plurality of magnetically encoded regionsarranged along the reciprocating object. According to this embodiment,an asymmetric configuration and arrangement of magnetic field detectorswith respect to corresponding magnetically encoded regions in areference state of the reciprocating object is achieved. For example, afirst magnetically encoded region may have its central axis aligned inaccordance with a central axis of a corresponding magnetic fielddetector. For a second magnetically encoded region, in the referencestate, the central axis may be displaced with respect to a central axisof a corresponding magnetic field detector, and so on. Such a geometricoffset may be used to improve the performance of the position sensordevice, since the signals occur in a timely shifted manner, thusincreasing the amount of detection information and allowing to refinethe position determination.

The number of magnetically encoded regions may differ from the number ofmagnetic field detectors. For example, there may be provided threemagnetically encoded regions and four magnetic field detectors. Or, twomagnetic field detectors may be provided for each of the magneticallyencoded regions. Or, a plurality of magnetic field detectors may beprovided for each of the magnetically encoded regions, wherein thenumber of magnetically field detectors for any of the magneticallyencoded regions may differ for different magnetically encoded regions.

In the position sensor device, the reciprocating object can be apush-pull-rod in a gearbox of a vehicle. In an automatic automotivegearbox system, the position of the various tooth-wheels (gear-wheels)may be changed by push-pull-rods. The actual position of such a rod canbe measured with the position sensor device.

In the following, exemplary embodiments of the position sensor array ofthe invention will be described. These embodiments apply also for theposition sensor device, for the concrete processing apparatus and forthe method of determining a position of a reciprocating object.

In the position sensor array, the reciprocating object may be a shaft.Such a shaft can be driven by an engine, and may be, for example, ahydraulically driven work cylinder of a concrete processing apparatus.

The magnetically encoding region may be provided along a part of thelength of the reciprocating object. In other words, any of themagnetically encoded regions may extend along a portion of thereciprocating object in longitudinal direction, wherein another portionof the reciprocating object is free of a magnetically encoding region.

Alternatively, the magnetically encoded region may be provided along theentire length of the reciprocating object. According to this embodiment,the whole reciprocating object is magnetized.

The reciprocating object may be divided into a plurality of equallyspaced segments, each segment comprising one magnetically encodedregion, the magnetically encoded regions of the segments being arrangedin an asymmetric manner. For instance, three segments may be provided,wherein the first segment has a magnetically encoded region in the firstthird of its length, the second segment has a magnetically encodedregion in the middle third of its length and the third and last segmenthas the magnetically encoded region in the last third of its length.Such a configuration gradually increases the spacing between consecutivemarkers yielding a characteristic signal pattern allowing an accurateestimation of the reciprocating shaft position.

Further, a control unit may be provided in the position sensor arrayadapted to control the reciprocation of the reciprocating object basedon the determined position of the reciprocating object which is providedto the control unit by the position sensor device. Thus, the output ofthe position sensor device, namely the present position of thereciprocating object, is provided to the control unit as feedbackinformation. Based on this back coupling, the control unit can adjust acontrolling signal for controlling the reciprocation of thereciprocating object to ensure a proper operation of the reciprocatingobject.

In the following, exemplary embodiments of the concrete processingapparatus will be described. These embodiments also apply to theposition sensor device, the position sensor array and the method fordetermining a position of a reciprocating object.

In a concrete processing apparatus, a control unit may be providedadapted to control the reciprocation of the reciprocating shaft based onthe position of the reciprocating shaft which is provided to the controlunit by the position sensor device.

The concrete processing apparatus may further comprise a vehicle onwhich the concrete processing chamber, the reciprocating shaft and theposition sensor device may be mounted. Thus, a mobile concreteprocessing apparatus provided on a vehicle is created which can beflexibly transported to a place of installation.

The concrete processing apparatus of the invention may further comprisea further reciprocation shaft arranged in the concrete processingchamber adapted to reciprocate to mix concrete material. Thereciprocating shaft and the further reciprocating shaft are operable ina countercyclical manner. In other words, two reciprocating shafts orcylinders may be provided to mix concrete material, wherein the tworeciprocating shafts move in opposite directions in each operationstate. For instance, in a scenario in which the first reciprocationshaft moves in a forward direction, the second reciprocation shaft movesin the backwards direction, and vice versa. By taking this measure, anexcellent mixture of the concrete in the concrete processing apparatusis achieved. In order to accurately control the mixing of the concreteby the two reciprocating shafts, it is necessary to control the motionof the reciprocating shafts on the basis of estimated positioninformation generated by the position sensor device. Particularly, in anoperation state of the reciprocating shafts, in which they change theirmotion direction, it is particularly important to control the operationof the reciprocating shafts, since the energy consumption in this stateis particularly high.

In the following, further aspects of the invention will be describedwhich fall under the scope of the invention.

An amplitude, an algebraic sign, and/or a slope of a detected signal canbe used to derive direction information, i.e. to determine if thereciprocating object moves from a first direction to a second directionor from the second direction to the first direction. According to theinvention, one signal or a plurality of signals may beanalyzed/evaluated to allow an unambiguous assignment of the detectionsignals to a position of the reciprocating object to be detected. Thearrangement of the magnetic field detectors and of the magneticallyencoded regions is for instance selected such that a signal sequence ofthe magnetic field detectors is unique with respect to a particularposition of the reciprocating object.

The magnetic position detection principle of the invention, in contrastto optical or mechanical marker detection methods, is abrasion free andoperates without errors even in a scenario in which critical conditions(like concrete powder or other kind of dirt) are present.

Further, the magnetic position detection principle of the invention canbe used in a wide temperature range. The only physical restrictionconcerning the temperature range in which the magnetic detectionprinciple of the invention may be implemented is the Currie temperatureof the used magnetic material. Thus, the magnetic components of thesystem of the invention can be used—with a reciprocating object made ofindustrial steel—up to 400° C. and more. A limiting factor for themaximum operation temperature of the system of the invention may be thetemperature up to which an isolation of a coil as a magnetic fielddetector keeps intact. However, with available coils, a temperature ofat least 210° C. can be obtained. Thus, the system of the invention isvery temperature stable. Since the detection principle of the inventionis contactless, a cooling element can be provided in an environment inwhich very high temperatures are present. Such a cooling element can bea water cooling element, for instance.

The lengths of a reciprocating shaft for an implementation in a concreteprocessing apparatus may be 5 meters and more.

In principle, using one magnetic field detector, for instance one coil,is sufficient. However, in order to eliminate the influence of themagnetic field of the earth, two detection coils may be used withoppositely oriented coil axis, so that the influence of the earthmagnetic field can be eliminated by considering the two signals of thetwo coils. The detection of the position can include counting the numberof markers which pass one or more magnetic field detectors per time.

The above and other aspects, objects, features and advantages of thepresent invention will become apparent from the following descriptionand the appended claim, taken in conjunction with the accompanyingdrawings in which like parts or elements are denoted by like referencenumbers.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and constitute a part of thespecification illustrate embodiments of the invention.

In the drawings:

FIG. 1 shows a torque sensor with a sensor element according to anexemplary embodiment of the present invention for explaining a method ofmanufacturing a torque sensor according to an exemplary embodiment ofthe present invention.

FIG. 2 a shows an exemplary embodiment of a sensor element of a torquesensor according to the present invention for further explaining aprinciple of the present invention and an aspect of an exemplaryembodiment of a manufacturing method of the present invention.

FIG. 2 b shows a cross-sectional view along AA′ of FIG. 2 a.

FIG. 3 a shows another exemplary embodiment of a sensor element of atorque sensor according to the present invention for further explaininga principle of the present invention and an exemplary embodiment of amethod of manufacturing a torque sensor according to the presentinvention.

FIG. 3 b shows a cross-sectional representation along BB′ of FIG. 3 a.

FIG. 4 shows a cross-sectional representation of the sensor element ofthe torque sensor of FIGS. 2 a and 3 a manufactured in accordance with amethod according to an exemplary embodiment of the present invention.

FIG. 5 shows another exemplary embodiment of a sensor element of atorque sensor according to the present invention for further explainingan exemplary embodiment of a manufacturing method of manufacturing atorque sensor according to the present invention.

FIG. 6 shows another exemplary embodiment of a sensor element of atorque sensor according to the present invention for further explainingan exemplary embodiment of a manufacturing method for a torque sensoraccording to the present invention.

FIG. 7 shows a flow-chart for further explaining an exemplary embodimentof a method of manufacturing a torque sensor according to the presentinvention.

FIG. 8 shows a current versus time diagram for further explaining amethod according to an exemplary embodiment of the present invention.

FIG. 9 shows another exemplary embodiment of a sensor element of atorque sensor according to the present invention with an electrodesystem according to an exemplary embodiment of the present invention.

FIG. 10 a shows another exemplary embodiment of a torque sensoraccording to the present invention with an electrode system according toan exemplary embodiment of the present invention.

FIG. 10 b shows the sensor element of FIG. 10 a after the application ofcurrent surges by means of the electrode system of FIG. 10 a.

FIG. 11 shows another exemplary embodiment of a torque sensor elementfor a torque sensor according to the present invention.

FIG. 12 shows a schematic diagram of a sensor element of a torque sensoraccording to another exemplary embodiment of the present inventionshowing that two magnetic fields may be stored in the shaft and runningin endless circles.

FIG. 13 is another schematic diagram for illustrating PCME sensingtechnology using two counter cycle or magnetic field loops which may begenerated in accordance with a manufacturing method according to thepresent invention.

FIG. 14 shows another schematic diagram for illustrating that when nomechanical stress is applied to the sensor element according to anexemplary embodiment of the present invention, magnetic flux lines arerunning in its original paths.

FIG. 15 is another schematic diagram for further explaining a principleof an exemplary embodiment of the present invention.

FIG. 16 is another schematic diagram for further explaining theprinciple of an exemplary embodiment of the present invention.

FIGS. 17-22 are schematic representations for further explaining aprinciple of an exemplary embodiment of the present invention.

FIG. 23 is another schematic diagram for explaining a principle of anexemplary embodiment of the present invention.

FIGS. 24, 25 and 26 are schematic diagrams for further explaining aprinciple of an exemplary embodiment of the present invention.

FIG. 27 is a current versus time diagram for illustrating a currentpulse which may be applied to a sensor element according to amanufacturing method according to an exemplary embodiment of the presentinvention.

FIG. 28 shows an output signal versus current pulse length diagramaccording to an exemplary embodiment of the present invention.

FIG. 29 shows a current versus time diagram with current pulsesaccording to an exemplary embodiment of the present invention which maybe applied to sensor elements according to a method of the presentinvention.

FIG. 30 shows another current versus time diagram showing an exemplaryembodiment of a current pulse applied to a sensor element such as ashaft according to a method of an exemplary embodiment of the presentinvention.

FIG. 31 shows a signal and signal efficiency versus current diagram inaccordance with an exemplary embodiment of the present invention.

FIG. 32 is a cross-sectional view of a sensor element having anexemplary PCME electrical current density according to an exemplaryembodiment of the present invention.

FIG. 33 shows a cross-sectional view of a sensor element and anelectrical pulse current density at different and increasing pulsecurrent levels according to an exemplary embodiment of the presentinvention.

FIGS. 34 a and 34 b show a spacing achieved with different currentpulses of magnetic flows in sensor elements according to the presentinvention.

FIG. 35 shows a current versus time diagram of a current pulse as it maybe applied to a sensor element according to an exemplary embodiment ofthe present invention.

FIG. 36 shows an electrical multi-point connection to a sensor elementaccording to an exemplary embodiment of the present invention.

FIG. 37 shows a multi-channel electrical connection fixture with springloaded contact points to apply a current pulse to the sensor elementaccording to an exemplary embodiment of the present invention.

FIG. 38 shows an electrode system with an increased number of electricalconnection points according to an exemplary embodiment of the presentinvention.

FIG. 39 shows an exemplary embodiment of the electrode system of FIG.37.

FIG. 40 shows shaft processing holding clamps used for a methodaccording to an exemplary embodiment of the present invention.

FIG. 41 shows a dual field encoding region of a sensor element accordingto the present invention.

FIG. 42 shows a process step of a sequential dual field encodingaccording to an exemplary embodiment of the present invention.

FIG. 43 shows another process step of the dual field encoding accordingto another exemplary embodiment of the present invention.

FIG. 44 shows another exemplary embodiment of a sensor element with anillustration of a current pulse application according to anotherexemplary embodiment of the present invention.

FIG. 45 shows schematic diagrams for describing magnetic flux directionsin sensor elements according to the present invention when no stress isapplied.

FIG. 46 shows magnetic flux directions of the sensor element of FIG. 45when a force is applied.

FIG. 47 shows the magnetic flux inside the PCM encoded shaft of FIG. 45when the applied torque direction is changing.

FIG. 48 shows a 6-channel synchronized pulse current driver systemaccording to an exemplary embodiment of the present invention.

FIG. 49 shows a simplified representation of an electrode systemaccording to another exemplary embodiment of the present invention.

FIG. 50 is a representation of a sensor element according to anexemplary embodiment of the present invention.

FIG. 51 is another exemplary embodiment of a sensor element according tothe present invention having a PCME process sensing region with twopinning field regions.

FIG. 52 is a schematic representation for explaining a manufacturingmethod according to an exemplary embodiment of the present invention formanufacturing a sensor element with an encoded region and pinningregions.

FIG. 53 is another schematic representation of a sensor elementaccording to an exemplary embodiment of the present inventionmanufactured in accordance with a manufacturing method according to anexemplary embodiment of the present invention.

FIG. 54 is a simplified schematic representation for further explainingan exemplary embodiment of the present invention.

FIG. 55 is another simplified schematic representation for furtherexplaining an exemplary embodiment of the present invention.

FIG. 56 shows an application of a torque sensor according to anexemplary embodiment of the present invention in a gear box of a motor.

FIG. 57 shows a torque sensor according to an exemplary embodiment ofthe present invention.

FIG. 58 shows a schematic illustration of components of a non-contacttorque sensing device according to an exemplary embodiment of thepresent invention.

FIG. 59 shows components of a sensing device according to an exemplaryembodiment of the present invention.

FIG. 60 shows arrangements of coils with a sensor element according toan exemplary embodiment of the present invention.

FIG. 61 shows a single channel sensor electronics according to anexemplary embodiment of the present invention.

FIG. 62 shows a dual channel, short circuit protected system accordingto an exemplary embodiment of the present invention.

FIG. 63 shows a sensor according to another exemplary embodiment of thepresent invention.

FIG. 64 illustrates an exemplary embodiment of a secondary sensor unitassembly according to an exemplary embodiment of the present invention.

FIG. 65 illustrates two configurations of a geometrical arrangement ofprimary sensor and secondary sensor according to an exemplary embodimentof the present invention.

FIG. 66 is a schematic representation for explaining that a spacingbetween the secondary sensor unit and the sensor host is preferably assmall as possible.

FIG. 67 is an embodiment showing a primary sensor encoding equipment.

FIG. 68 shows a position sensor array according to a first embodiment ofthe invention.

FIG. 69 shows a position sensor array according to a second embodimentof the invention.

FIG. 70 shows a position sensor array according to a third embodiment ofthe invention.

FIG. 71 shows a position sensor array according to a forth embodiment ofthe invention.

FIG. 72 shows a position sensor array according to a fifth embodiment ofthe invention.

FIG. 73 shows a diagram illustrating a detection signal as detected bythe magnet field detection coil of the position sensor array accordingto the forth embodiment of the invention.

FIG. 74 shows a position sensor array according to a sixth embodiment ofthe invention.

FIG. 75 shows a diagram illustrating a detection signal as detected bythe magnet field detection coil of the position sensor array accordingto the sixth embodiment of the invention.

FIG. 76 shows a position sensor array according to a seventh embodimentof the invention.

FIG. 77 shows a concrete processing apparatus according to a firstembodiment of the invention.

FIG. 78 shows a concrete processing apparatus according to a secondembodiment of the invention.

FIG. 79 and FIG. 80 show schematic views illustrating a sequence ofsignals captured by three magnetic field detectors generated by sixmagnetic encoded regions provided on a reciprocating shaft of a positionsensor array according to an eighth embodiment of the invention.

FIG. 81 and FIG. 82 show schematic views illustrating a sequence ofsignals captured by two magnetic field detectors generated by sixmagnetic encoded regions provided on a reciprocating shaft of a positionsensor array according to a ninth embodiment of the invention.

FIG. 83 shows a schematic view illustrating a sequence of signalscaptured by one magnetic field detector generated by six magneticencoded regions provided on a reciprocating shaft of a position sensorarray according to a tenth embodiment of the invention.

FIG. 84 to FIG. 86 show hollow tubes as reciprocating objects withdifferent embodiments for magnetic encoded regions arranged inside thehollow tube.

FIG. 87, FIG. 88 show a position sensor array according to an eleventhembodiment of the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION

It is disclosed a sensor having a sensor element such as a shaft whereinthe sensor element may be manufactured in accordance with the followingmanufacturing steps

-   -   applying a first current pulse to the sensor element;    -   wherein the first current pulse is applied such that there is a        first current flow in a first direction along a longitudinal        axis of the sensor element;    -   wherein the first current pulse is such that the application of        the current pulse generates a magnetically encoded region in the        sensor element.

It is disclosed that a further second current pulse may be applied tothe sensor element. The second current pulse may be applied such thatthere is a second current flow in a direction along the longitudinalaxis of the sensor element.

It is disclosed that the directions of the first and second currentpulses may be opposite to each other. Also, each of the first and secondcurrent pulses may have a raising edge and a falling edge. For instance,the raising edge is steeper than the falling edge.

It is believed that the application of a current pulse may cause amagnetic field structure in the sensor element such that in across-sectional view of the sensor element, there is a first circularmagnetic flow having a first direction and a second magnetic flow havinga second direction. The radius of the first magnetic flow may be largerthan the radius of the second magnetic flow. In shafts having anon-circular cross-section, the magnetic flow is not necessarilycircular but may have a form essentially corresponding to and beingadapted to the cross-section of the respective sensor element.

It is believed that if no torque is applied to a sensor element, thereis no magnetic field or essentially no magnetic field detectable at theoutside. When a torque or force is applied to the sensor element, thereis a magnetic field emanated from the sensor element which can bedetected by means of suitable coils. This will be described in furtherdetail in the following.

A torque sensor may have a circumferential surface surrounding a coreregion of the sensor element. The first current pulse is introduced intothe sensor element at a first location at the circumferential surfacesuch that there is a first current flow in the first direction in thecore region of the sensor element. The first current pulse is dischargedfrom the sensor element at a second location at the circumferentialsurface. The second location is at a distance in the first directionfrom the first location. The second current pulse may be introduced intothe sensor element at the second location or adjacent to the secondlocation at the circumferential surface such that there is the secondcurrent flow in the second direction in the core region or adjacent tothe core region in the sensor element. The second current pulse may bedischarged from the sensor element at the first location or adjacent tothe first location at the circumferential surface.

As already indicated above, the sensor element may be a shaft. The coreregion of such shaft may extend inside the shaft along its longitudinalextension such that the core region surrounds a center of the shaft. Thecircumferential surface of the shaft is the outside surface of theshaft. The first and second locations are respective circumferentialregions at the outside of the shaft. There may be a limited number ofcontact portions which constitute such regions. For instance, realcontact regions may be provided, for example, by providing electroderegions made of brass rings as electrodes. Also, a core of a conductormay be looped around the shaft to provide for a good electric contactbetween a conductor such as a cable without isolation and the shaft.

The first current pulse and also the second current pulse may be notapplied to the sensor element at an end face of the sensor element. Thefirst current pulse may have a maximum between 40 and 1400 Ampere orbetween 60 and 800 Ampere or between 75 and 600 Ampere or between 80 and500 Ampere. The current pulse may have a maximum such that anappropriate encoding is caused to the sensor element. However, due todifferent materials which may be used and different forms of the sensorelement and different dimensions of the sensor element, a maximum of thecurrent pulse may be adjusted in accordance with these parameters. Thesecond pulse may have a similar maximum or may have a maximumapproximately 10, 20, 30, 40 or 50% smaller than the first maximum.However, the second pulse may also have a higher maximum such as 10, 20,40, 50, 60 or 80% higher than the first maximum.

A duration of those pulses may be the same. However, it is possible thatthe first pulse has a significant longer duration than the second pulse.However, it is also possible that the second pulse has a longer durationthan the first pulse.

The first and/or second current pulses may have a first duration fromthe start of the pulse to the maximum and may have a second durationfrom the maximum to essentially the end of the pulse. The first durationmay be significantly longer than the second duration. For example, thefirst duration may be smaller than 300 ms wherein the second durationmay be larger than 300 ms. However, it is also possible that the firstduration is smaller than 200 ms whereas the second duration is largerthan 400 ms. Also, the first duration may be between 20 to 150 mswherein the second duration may be between 180 to 700 ms.

As already indicated above, it is possible to apply a plurality of firstcurrent pulses but also a plurality of second current pulses. The sensorelement may be made of steel whereas the steel may comprise nickel. Thesensor material used for the primary sensor or for the sensor elementmay be 50NiCr13 or X4CrNi13-4 or X5CrNiCuNb16-4 or X20CrNi17-4 orX46Cr13 or X20Cr13 or 14NiCr14 or S155 as set forth in DIN 1.2721 or1.4313 or 1.4542 or 1.2787 or 1.4034 or 1.4021 or 1.5752 or 1.6928.

The first current pulse may be applied by means of an electrode systemhaving at least a first electrode and a second electrode. The firstelectrode is located at the first location or adjacent to the firstlocation and the second electrode is located at the second location oradjacent to the second location.

Each of the first and second electrodes may have a plurality ofelectrode pins. The plurality of electrode pins of each of the first andsecond electrodes may be arranged circumferentially around the sensorelement such that the sensor element is contacted by the electrode pinsof the first and second electrodes at a plurality of contact points atan outer circumferential surface of the shaft at the first and secondlocations.

As indicated above, instead of electrode pins laminar or two-dimensionalelectrode surfaces may be applied. For instance, electrode surfaces areadapted to surfaces of the shaft such that a good contact between theelectrodes and the shaft material may be ensured.

At least one of the first current pulse and at least one of the secondcurrent pulse may be applied to the sensor element such that the sensorelement has a magnetically encoded region such that in a directionessentially perpendicular to a surface of the sensor element, themagnetically encoded region of the sensor element has a magnetic fieldstructure such that there is a first magnetic flow in a first directionand a second magnetic flow in a second direction. The first directionmay be opposite to the second direction.

In a cross-sectional view of the sensor element, there may be a firstcircular magnetic flow having the first direction and a first radius anda second circular magnetic flow having the second direction and a secondradius. The first radius may be larger than the second radius.

Furthermore, the sensor elements may have a first pinning zone adjacentto the first location and a second pinning zone adjacent to the secondlocation.

The pinning zones may be manufactured in accordance with the followingmanufacturing method. According to this method, for forming the firstpinning zone, at the first location or adjacent to the first location, athird current pulse is applied on the circumferential surface of thesensor element such that there is a third current flow in the seconddirection. The third current flow is discharged from the sensor elementat a third location which is displaced from the first location in thesecond direction.

For forming the second pinning zone, at the second location or adjacentto the second location, a forth current pulse may be applied on thecircumferential surface to the sensor element such that there is a forthcurrent flow in the first direction. The forth current flow isdischarged at a forth location which is displaced from the secondlocation in the first direction.

A torque sensor may be provided comprising a first sensor element with amagnetically encoded region wherein the first sensor element has asurface. In a direction essentially perpendicular to the surface of thefirst sensor element, the magnetically encoded region of the firstsensor element may have a magnetic field structure such that there is afirst magnetic flow in a first direction and a second magnetic flow in asecond direction. The first and second directions may be opposite toeach other.

The torque sensor may further comprise a second sensor element with atleast one magnetic field detector. The second sensor element may beadapted for detecting variations in the magnetically encoded region.More precisely, the second sensor element may be adapted for detectingvariations in a magnetic field emitted from the magnetically encodedregion of the first sensor element.

The magnetically encoded region may extend longitudinally along asection of the first sensor element, but does not extend from one endface of the first sensor element to the other end face of the firstsensor element. In other words, the magnetically encoded region does notextend along all of the first sensor element but only along a sectionthereof.

The first sensor element may have variations in the material of thefirst sensor element caused by at least one current pulse or surgeapplied to the first sensor element for altering the magneticallyencoded region or for generating the magnetically encoded region. Suchvariations in the material may be caused, for example, by differingcontact resistances between electrode systems for applying the currentpulses and the surface of the respective sensor element. Such variationsmay, for example, be burn marks or color variations or signs of anannealing.

The variations may be at an outer surface of the sensor element and notat the end faces of the first sensor element since the current pulsesare applied to outer surface of the sensor element but not to the endfaces thereof.

A shaft for a magnetic sensor may be provided having, in a cross-sectionthereof, at least two circular magnetic loops running in oppositedirection. Such shaft is believed to be manufactured in accordance withthe above-described manufacturing method.

Furthermore, a shaft may be provided having at least two circularmagnetic loops which are arranged concentrically.

A shaft for a torque sensor may be provided which is manufactured inaccordance with the following manufacturing steps where firstly a firstcurrent pulse is applied to the shaft. The first current pulse isapplied to the shaft such that there is a first current flow in a firstdirection along a longitudinal axis of the shaft. The first currentpulse is such that the application of the current pulse generates amagnetically encoded region in the shaft. This may be made by using anelectrode system as described above and by applying current pulses asdescribed above.

An electrode system may be provided for applying current surges to asensor element for a torque sensor, the electrode system having at leasta first electrode and a second electrode wherein the first electrode isadapted for location at a first location on an outer surface of thesensor element. A second electrode is adapted for location at a secondlocation on the outer surface of the sensor element. The first andsecond electrodes are adapted for applying and discharging at least onecurrent pulse at the first and second locations such that current flowswithin a core region of the sensor element are caused. The at least onecurrent pulse is such that a magnetically encoded region is generated ata section of the sensor element.

The electrode system may comprise at least two groups of electrodes,each comprising a plurality of electrode pins. The electrode pins ofeach electrode are arranged in a circle such that the sensor element iscontacted by the electrode pins of the electrode at a plurality ofcontact points at an outer surface of the sensor element.

The outer surface of the sensor element does not include the end facesof the sensor element.

FIG. 1 shows an exemplary embodiment of a torque sensor according to thepresent invention. The torque sensor comprises a first sensor element orshaft 2 having a rectangular cross-section. The first sensor element 2extends essentially along the direction indicated with X. In a middleportion of the first sensor element 2, there is the encoded region 4.The first location is indicated by reference numeral 10 and indicatesone end of the encoded region and the second location is indicated byreference numeral 12 which indicates another end of the encoded regionor the region to be magnetically encoded 4. Arrows 14 and 16 indicatethe application of a current pulse. As indicated in FIG. 1, a firstcurrent pulse is applied to the first sensor element 2 at an outerregion adjacent or close to the first location 10. For instance, as willbe described in further detail later on, the current is introduced intothe first sensor element 2 at a plurality of points or regions close tothe first location and surrounding the outer surface of the first sensorelement 2 along the first location 10. As indicated with arrow 16, thecurrent pulse is discharged from the first sensor element 2 close oradjacent or at the second location 12 for instance at a plurality orlocations along the end of the region 4 to be encoded. As alreadyindicated before, a plurality of current pulses may be applied insuccession they may have alternating directions from location 10 tolocation 12 or from location 12 to location 10.

Reference numeral 6 indicates a second sensor element which is forinstance a coil connected to a controller electronic 8. The controllerelectronic 8 may be adapted to further process a signal output by thesecond sensor element 6 such that an output signal may output from thecontrol circuit corresponding to a torque applied to the first sensorelement 2. The control circuit 8 may be an analog or digital circuit.The second sensor element 6 is adapted to detect a magnetic fieldemitted by the encoded region 4 of the first sensor element.

It is believed that, as already indicated above, if there is no stressor force applied to the first sensor element 2, there is essentially nofield detected by the second sensor element 6. However, in case a stressor a force is applied to the secondary sensor element 2, there is avariation in the magnetic field emitted by the encoded region such thatan increase of a magnetic field from the presence of almost no field isdetected by the second sensor element 6.

It has to be noted that according to other exemplary embodiments of thepresent invention, even if there is no stress applied to the firstsensor element, it may be possible that there is a magnetic fielddetectable outside or adjacent to the encoded region 4 of the firstsensor element 2. However, it is to be noted that a stress applied tothe first sensor element 2 causes a variation of the magnetic fieldemitted by the encoded region 4.

In the following, with reference to FIGS. 2 a, 2 b, 3 a, 3 b and 4, amethod of manufacturing a torque sensor according to an exemplaryembodiment of the present invention will be described. In particular,the method relates to the magnetization of the magnetically encodedregion 4 of the first sensor element 2.

As may be taken from FIG. 2 a, a current I is applied to an end regionof a region 4 to be magnetically encoded. This end region as alreadyindicated above is indicated with reference numeral 10 and may be acircumferential region on the outer surface of the first sensor element2. The current I is discharged from the first sensor element 2 atanother end area of the magnetically encoded region (or of the region tobe magnetically encoded) which is indicated by reference numeral 12 andalso referred to a second location. The current is taken from the firstsensor element at an outer surface thereof, for instancecircumferentially in regions close or adjacent to location 12. Asindicated by the dashed line between locations 10 and 12, the current Iintroduced at or along location 10 into the first sensor element flowsthrough a core region or parallel to a core region to location 12. Inother words, the current I flows through the region 4 to be encoded inthe first sensor element 2.

FIG. 2 b shows a cross-sectional view along AA′. In the schematicrepresentation of FIG. 2 b, the current flow is indicated into the planeof the FIG. 2 b as a cross. Here, the current flow is indicated in acenter portion of the cross-section of the first sensor element 2. It isbelieved that this introduction of a current pulse having a form asdescribed above or in the following and having a maximum as describedabove or in the following causes a magnetic flow structure 20 in thecross-sectional view with a magnetic flow direction into one directionhere into the clockwise direction. The magnetic flow structure 20depicted in FIG. 2 b is depicted essentially circular. However, themagnetic flow structure 20 may be adapted to the actual cross-section ofthe first sensor element 2 and may be, for example, more elliptical.

FIGS. 3 a and 3 b show a step of the method according to an exemplaryembodiment of the present invention which may be applied after the stepdepicted in FIGS. 2 a and 2 b. FIG. 3 a shows a first sensor elementaccording to an exemplary embodiment of the present invention with theapplication of a second current pulse and FIG. 3 b shows across-sectional view along BB′ of the first sensor element 2.

As may be taken from FIG. 3 a, in comparison to FIG. 2 a, in FIG. 3 a,the current I indicated by arrow 16 is introduced into the sensorelement 2 at or adjacent to location 12 and is discharged or taken fromthe sensor element 2 at or adjacent to the location 10. In other words,the current is discharged in FIG. 3 a at a location where it wasintroduced in FIG. 2 a and vice versa. Thus, the introduction anddischarging of the current I into the first sensor element 2 in FIG. 3 amay cause a current through the region 4 to be magnetically encodedopposite to the respective current flow in FIG. 2 a.

The current is indicated in FIG. 3 b in a core region of the sensorelement 2. As may be taken from a comparison of FIGS. 2 b and 3 b, themagnetic flow structure 22 has a direction opposite to the current flowstructure 20 in FIG. 2 b.

As indicated before, the steps depicted in FIGS. 2 a, 2 b and 3 a and 3b may be applied individually or may be applied in succession of eachother. When firstly, the step depicted in FIGS. 2 a and 2 b is performedand then the step depicted in FIGS. 3 a and 3 b, a magnetic flowstructure as depicted in the cross-sectional view through the encodedregion 4 depicted in FIG. 4 may be caused. As may be taken from FIG. 4,the two current flow structures 20 and 22 are encoded into the encodedregion together. Thus, in a direction essentially perpendicular to asurface of the first sensor element 2, in a direction to the core of thesensor element 2, there is a first magnetic flow having a firstdirection and then underlying there is a second magnetic flow having asecond direction. As indicated in FIG. 4, the flow directions may beopposite to each other.

Thus, if there is no torque applied to the first torque sensor element2, the two magnetic flow structures 20 and 22 may cancel each other suchthat there is essentially no magnetic field at the outside of theencoded region. However, in case a stress or force is applied to thefirst sensor element 2, the magnetic field structures 20 and 22 cease tocancel each other such that there is a magnetic field occurring at theoutside of the encoded region which may then be detected by means of thesecondary sensor element 6. This will be described in further detail inthe following.

FIG. 5 shows another exemplary of a first sensor element 2 according toan exemplary embodiment of the present invention as may be used in atorque sensor according to an exemplary embodiment which is manufacturedaccording to a manufacturing method according to an exemplary embodimentof the present invention. As may be taken from FIG. 5, the first sensorelement 2 has an encoded region 4 which is for instance encoded inaccordance with the steps and arrangements depicted in FIGS. 2 a, 2 b, 3a, 3 b and 4.

Adjacent to locations 10 and 12, there are provided pinning regions 42and 44. These regions 42 and 44 are provided for avoiding a fraying ofthe encoded region 4. In other words, the pinning regions 42 and 44 mayallow for a more definite beginning and end of the encoded region 4.

In short, the first pinning region 42 may be adapted by introducing acurrent 38 close or adjacent to the first location 10 into the firstsensor element 2 in the same manner as described, for example, withreference to FIG. 2 a. However, the current I is discharged from thefirst sensor element 2 at a first location 30 which is at a distancefrom the end of the encoded region close or at location 10. This furtherlocation is indicated by reference numeral 30. The introduction of thisfurther current pulse I is indicated by arrow 38 and the dischargingthereof is indicated by arrow 40. The current pulses may have the sameform shaping maximum as described above.

For generating the second pinning region 44, a current is introducedinto the first sensor element 2 at a location 32 which is at a distancefrom the end of the encoded region 4 close or adjacent to location 12.The current is then discharged from the first sensor element 2 at orclose to the location 12. The introduction of the current pulse I isindicated by arrows 34 and 36.

The pinning regions 42 and 44 may be such that the magnetic flowstructures of these pinning regions 42 and 44 are opposite to therespective adjacent magnetic flow structures in the adjacent encodedregion 4. As may be taken from FIG. 5, the pinning regions can be codedto the first sensor element 2 after the coding or the complete coding ofthe encoded region 4.

FIG. 6 shows another exemplary embodiment of the present invention wherethere is no encoding region 4. In other words, according to an exemplaryembodiment of the present invention, the pinning regions may be codedinto the first sensor element 2 before the actual coding of themagnetically encoded region 4.

FIG. 7 shows a simplified flow-chart of a method of manufacturing afirst sensor element 2 for a torque sensor according to an exemplaryembodiment of the present invention.

After the start in step S1, the method continues to step S2 where afirst pulse is applied as described as reference to FIGS. 2 a and 2 b.Then, after step S2, the method continues to step S3 where a secondpulse is applied as described with reference to FIGS. 3 a and 3 b.

Then, the method continues to step S4 where it is decided whether thepinning regions are to be coded to the first sensor element 2 or not. Ifit is decided in step S4 that there will be no pinning regions, themethod continues directly to step S7 where it ends.

If it is decided in step S4 that the pinning regions are to be coded tothe first sensor element 2, the method continues to step S5 where athird pulse is applied to the pinning region 42 in the directionindicated by arrows 38 and 40 and to pinning region 44 indicated by thearrows 34 and 36. Then, the method continues to step S6 where forcepulses applied to the respective pinning regions 42 and 44. To thepinning region 42, a force pulse is applied having a direction oppositeto the direction indicated by arrows 38 and 40. Also, to the pinningregion 44, a force pulse is applied to the pinning region having adirection opposite to the arrows 34 and 36. Then, the method continuesto step S7 where it ends.

In other words, for instance two pulses are applied for encoding of themagnetically encoded region 4. Those current pulses may have an oppositedirection. Furthermore, two pulses respectively having respectivedirections are applied to the pinning region 42 and to the pinningregion 44.

FIG. 8 shows a current versus time diagram of the pulses applied to themagnetically encoded region 4 and to the pinning regions. The positivedirection of the y-axis of the diagram in FIG. 8 indicates a currentflow into the x-direction and the negative direction of the y-axis ofFIG. 8 indicates a current flow in the y-direction.

As may be taken from FIG. 8 for coding the magnetically encoded region4, firstly a current pulse is applied having a direction into thex-direction. As may be taken from FIG. 8, the raising edge of the pulseis very sharp whereas the falling edge has a relatively long directionin comparison to the direction of the raising edge. As depicted in FIG.8, the pulse may have a maximum of approximately 75 Ampere. In otherapplications, the pulse may be not as sharp as depicted in FIG. 8.However, the raising edge should be steeper or should have a shorterduration than the falling edge.

Then, a second pulse is applied to the encoded region 4 having anopposite direction. The pulse may have the same form as the first pulse.However, a maximum of the second pulse may also differ from the maximumof the first pulse. Although the immediate shape of the pulse may bedifferent.

Then, for coding the pinning regions, pulses similar to the first andsecond pulse may be applied to the pinning regions as described withreference to FIGS. 5 and 6. Such pulses may be applied to the pinningregions simultaneously but also successfully for each pinning region. Asdepicted in FIG. 8, the pulses may have essentially the same form as thefirst and second pulses. However, a maximum may be smaller.

FIG. 9 shows another exemplary embodiment of a first sensor element of atorque sensor according to an exemplary embodiment of the presentinvention showing an electrode arrangement for applying the currentpulses for coding the magnetically encoded region 4. As may be takenfrom FIG. 9, a conductor without an isolation may be looped around thefirst sensor element 2 which is may be taken from FIG. 9 may be acircular shaft having a circular cross-section. For ensuring a close fitof the conductor on the outer surface of the first sensor element 2, theconductor may be clamped as shown by arrows 64.

FIG. 10 a shows another exemplary embodiment of a first sensor elementaccording to an exemplary embodiment of the present invention.Furthermore, FIG. 10 a shows another exemplary embodiment of anelectrode system according to an exemplary embodiment of the presentinvention. The electrode system 80 and 82 depicted in FIG. 10 a contactsthe first sensor element 2 which has a triangular cross-section with twocontact points at each phase of the triangular first sensor element ateach side of the region 4 which is to be encoded as magnetically encodedregion. Overall, there are six contact points at each side of the region4. The individual contact points may be connected to each other and thenconnected to one individual contact points.

If there is only a limited number of contact points between theelectrode system and the first sensor element 2 and if the currentpulses applied are very high, differing contact resistances between thecontacts of the electrode systems and the material of the first sensorelement 2 may cause burn marks at the first sensor element 2 at contactpoint to the electrode systems. These burn marks 90 may be colorchanges, may be welding spots, may be annealed areas or may simply beburn marks. According to an exemplary embodiment of the presentinvention, the number of contact points is increased or even a contactsurface is provided such that such burn marks 90 may be avoided.

FIG. 11 shows another exemplary embodiment of a first sensor element 2which is a shaft having a circular cross-section according to anexemplary embodiment of the present invention. As may be taken from FIG.11, the magnetically encoded region is at an end region of the firstsensor element 2. According to an exemplary embodiment of the presentinvention, the magnetically encoded region 4 is not extend over the fulllength of the first sensor element 2. As may be taken from FIG. 11, itmay be located at one end thereof. However, it has to be noted thataccording to an exemplary embodiment of the present invention, thecurrent pulses are applied from an outer circumferential surface of thefirst sensor element 2 and not from the end face 100 of the first sensorelement 2.

In the following, the so-called PCME (“Pulse-Current-ModulatedEncoding”) Sensing Technology will be described in detail, which can,according to an exemplary embodiment of the invention, be implemented tomagnetize a magnetizable object which is then partially demagnetizedaccording to the invention. In the following, the PCME technology willpartly described in the context of torque sensing. However, this conceptmay implemented in the context of position sensing as well.

In this description, there are a number of acronyms used as otherwisesome explanations and descriptions may be difficult to read. While theacronyms “ASIC”, “IC”, and “PCB” are already market standarddefinitions, there are many terms that are particularly related to themagnetostriction based NCT sensing technology. It should be noted thatin this description, when there is a reference to NCT technology or toPCME, it is referred to exemplary embodiments of the present invention.

Table 1 shows a list of abbreviations used in the following descriptionof the PCME technology.

TABLE 1 List of abbreviations Acronym Description Category ASICApplication Specific IC Electronics DF Dual Field Primary Sensor EMFEarth Magnetic Field Test Criteria FS Full Scale Test Criteria Hot-Sensitivity to nearby Specification Spotting Ferro magnetic material ICIntegrated Circuit Electronics MFS Magnetic Field Sensor SensorComponent NCT Non Contact Torque Technology PCB Printed Circuit BoardElectronics PCME Pulse Current Modulated Encoding Technology POCProof-of-Concept RSU Rotational Signal Uniformity Specification SCSPSignal Conditioning & Electronics Signal Processing SF Single FieldPrimary Sensor SH Sensor Host Primary Sensor SPHC Shaft ProcessingHolding Clamp Processing Tool SSU Secondary Sensor Unit Sensor Component

The magnetic principle based mechanical-stress sensing technology allowsto design and to produce a wide range of “physical-parameter-sensors”(like Force Sensing, Torque Sensing, and Material Diagnostic Analysis)that can be applied where Ferro-Magnetic materials are used. The mostcommon technologies used to build “magnetic-principle-based” sensorsare: Inductive differential displacement measurement (requires torsionshaft), measuring the changes of the materials permeability, andmeasuring the magnetostriction effects.

Over the last 20 years a number of different companies have developedtheir own and very specific solution in how to design and how to producea magnetic principle based torque sensor (i.e. ABB, FAST, FrauenhoferInstitute, FT, Kubota, MDI, NCTE, RM, Siemens, and others). Thesetechnologies are at various development stages and differ in“how-it-works”, the achievable performance, the systems reliability, andthe manufacturing/system cost.

Some of these technologies require that mechanical changes are made tothe shaft where torque should be measured (chevrons), or rely on themechanical torsion effect (require a long shaft that twists undertorque), or that something will be attached to the shaft itself(press-fitting a ring of certain properties to the shaft surface), orcoating of the shaft surface with a special substance. No-one has yetmastered a high-volume manufacturing process that can be applied to(almost) any shaft size, achieving tight performance tolerances, and isnot based on already existing technology patents.

In the following, a magnetostriction principle based Non-Contact-Torque(NCI) Sensing Technology is described that offers to the user a wholehost of new features and improved performances, previously notavailable. This technology enables the realization of a fully-integrated(small in space), real-time (high signal bandwidth) torque measurement,which is reliable and can be produced at an affordable cost, at anydesired quantities. This technology is called: PCME (forPulse-Current-Modulated Encoding) or Magnetostriction Transversal TorqueSensor.

The PCME technology can be applied to the shaft without making anymechanical changes to the shaft, or without attaching anything to theshaft. Most important, the PCME technology can be applied to any shaftdiameter (most other technologies have here a limitation) and does notneed to rotate/spin the shaft during the encoding process (very simpleand low-cost manufacturing process) which makes this technology veryapplicable for high-volume application.

In the following, a Magnetic Field Structure (Sensor Principle) will bedescribed.

The sensor life-time depends on a “closed-loop” magnetic field design.The PCME technology is based on two magnetic field structures, storedabove each other, and running in opposite directions. When no torquestress or motion stress is applied to the shaft (also called SensorHost, or SH) then the SH will act magnetically neutral (no magneticfield can be sensed at the outside of the SH).

FIG. 12 shows that two magnetic fields are stored in the shaft andrunning in endless circles. The outer field runs in one direction, whilethe inner field runs in the opposite direction.

FIG. 13 illustrates that the PCME sensing technology uses twoCounter-Circular magnetic field loops that are stored on top of eachother (Picky-Back mode).

When mechanical stress (like reciprocation motion or torque) is appliedat both ends of the PCME magnetized SH (Sensor Host, or Shaft) then themagnetic flux lines of both magnetic structures (or loops) will tilt inproportion to the applied torque.

As illustrated in FIG. 14, when no mechanical stresses are applied tothe SH the magnetic flux lines are running in its original path. Whenmechanical stresses are applied the magnetic flux lines tilt inproportion to the applied stress (like linear motion or torque).

Depending on the applied torque direction (clockwise or anti-clockwise,in relation to the SH) the magnetic flux lines will either tilt to theright or tilt to the left. Where the magnetic flux lines reach theboundary of the magnetically encoded region, the magnetic flux linesfrom the upper layer will join-up with the magnetic flux lines from thelower layer and visa-versa. This will then form a perfectly controlledtoroidal shape.

The benefits of such a magnetic structure are:

-   -   Reduced (almost eliminated) parasitic magnetic field structures        when mechanical stress is applied to the SH (this will result in        better RSU performances).    -   Higher Sensor-Output Signal-Slope as there are two “active”        layers that compliment each other when generating a mechanical        stress related signal. Explanation: When using a single-layer        sensor design, the “tilted” magnetic flux lines that exit at the        encoding region boundary have to create a “return passage” from        one boundary side to the other. This effort effects how much        signal is available to be sensed and measured outside of the SH        with the secondary sensor unit.    -   There are almost no limitations on the SH (shaft) dimensions        where the PCME technology will be applied to. The dual layered        magnetic field structure can be adapted to any solid or hollow        shaft dimensions.    -   The physical dimensions and sensor performances are in a very        wide range programmable and therefore can be tailored to the        targeted application.    -   This sensor design allows to measure mechanical stresses coming        from all three dimensions axis, including in-line forces applied        to the shaft (applicable as a load-cell). Explanation: Earlier        magnetostriction sensor designs (for example from FAST        Technology) have been limited to be sensitive in 2 dimensional        axis only, and could not measure in-line forces.

Referring to FIG. 15, when torque is applied to the SH, the magneticflux lines from both Counter-Circular magnetic loops are connecting toeach other at the sensor region boundaries.

When mechanical torque stress is applied to the SH then the magneticfield will no longer run around in circles but tilt slightly inproportion to the applied torque stress. This will cause the magneticfield lines from one layer to connect to the magnetic field lines in theother layer, and with this form a toroidal shape.

Referring to FIG. 16, an exaggerated presentation is shown of how themagnetic flux line will form an angled toroidal structure when highlevels of torque are applied to the SH.

In the following, features and benefits of the PCM-Encoding (PCME)Process will be described.

The magnetostriction NCT sensing technology from NCTE according to thepresent invention offers high performance sensing features like:

-   -   No mechanical changes required on the Sensor Host (already        existing shafts can be used as they are)    -   Nothing has to be attached to the Sensor Host (therefore nothing        can fall off or change over the shaft-lifetime=high MTBF)    -   During measurement the SH can rotate, reciprocate or move at any        desired speed (no limitations on rpm)    -   Very good RSU (Rotational Signal Uniformity) performances    -   Excellent measurement linearity (up to 0.01% of FS)    -   High measurement repeatability    -   Very high signal resolution (better than 14 bit)    -   Very high signal bandwidth (better than 10 kHz)

Depending on the chosen type of magnetostriction sensing technology, andthe chosen physical sensor design, the mechanical power transmittingshaft (also called “Sensor Host” or in short “SH”) can be used “as is”without making any mechanical changes to it or without attachinganything to the shaft. This is then called a “true” Non-Contact-Torquemeasurement principle allowing the shaft to rotate freely at any desiredspeed in both directions.

The here described PCM-Encoding (PCME) manufacturing process accordingto an exemplary embodiment of the present invention provides additionalfeatures no other magnetostriction technology can offer (Uniqueness ofthis technology):

-   -   More then three times signal strength in comparison to        alternative magnetostriction encoding processes (like the “RS”        process from FAST).    -   Easy and simple shaft loading process (high manufacturing        through-put).    -   No moving components during magnetic encoding process (low        complexity manufacturing equipment=high MTBF, and lower cost).    -   Process allows NCT sensor to be “fine-tuning” to achieve target        accuracy of a fraction of one percent.    -   Manufacturing process allows shaft “pre-processing” and        “post-processing” in the same process cycle (high manufacturing        through-putt).    -   Sensing technology and manufacturing process is ratio-metric and        therefore is applicable to all shaft or tube diameters.    -   The PCM-Encoding process can be applied while the SH is already        assembled (depending on accessibility) (maintenance friendly).    -   Final sensor is insensitive to axial shaft movements (the actual        allowable axial shaft movement depends on the physical “length”        of the magnetically encoded region).    -   Magnetically encoded SH remains neutral and has little to non        magnetic field when no forces (like torque) are applied to the        SH.    -   Sensitive to mechanical forces in all three dimensional axis.

In the following, the Magnetic Flux Distribution in the SH will bedescribed.

The PCME processing technology is based on using electrical currents,passing through the SH (Sensor Host or Shaft) to achieve the desired,permanent magnetic encoding of the Ferro-magnetic material. To achievethe desired sensor performance and features a very specific and wellcontrolled electrical current is required. Early experiments that usedDC currents failed because of luck of understanding how small amountsand large amounts of DC electric current are travelling through aconductor (in this case the “conductor” is the mechanical powertransmitting shaft, also called Sensor Host or in short “SH”).

Referring to FIG. 17, an assumed electrical current density in aconductor is illustrated.

It is widely assumed that the electric current density in a conductor isevenly distributed over the entire cross-section of the conductor whenan electric current (DC) passes through the conductor.

Referring to FIG. 18, a small electrical current forming magnetic fieldthat ties current path in a conductor is shown.

It is our experience that when a small amount of electrical current (DC)is passing through the conductor that the current density is highest atthe centre of the conductor. The two main reasons for this are: Theelectric current passing through a conductor generates a magnetic fieldthat is tying together the current path in the centre of the conductor,and the impedance is the lowest in the centre of the conductor.

Referring to FIG. 19, a typical flow of small electrical currents in aconductor is illustrated.

In reality, however, the electric current may not flow in a “straight”line from one connection pole to the other (similar to the shape ofelectric lightening in the sky).

At a certain level of electric current the generated magnetic field islarge enough to cause a permanent magnetization of the Ferro-magneticshaft material. As the electric current is flowing near or at the centreof the SH, the permanently stored magnetic field will reside at the samelocation: near or at the centre of the SH. When now applying mechanicaltorque or linear force for oscillation/reciprocation to the shaft, thenshaft internally stored magnetic field will respond by tilting itsmagnetic flux path in accordance to the applied mechanical force. As thepermanently stored magnetic field lies deep below the shaft surface themeasurable effects are very small, not uniform and therefore notsufficient to build a reliable NCT sensor system.

Referring to FIG. 20, a uniform current density in a conductor atsaturation level is shown.

Only at the saturation level is the electric current density (whenapplying DC) evenly distributed at the entire cross section of theconductor. The amount of electrical current to achieve this saturationlevel is extremely high and is mainly influenced by the cross sectionand conductivity (impedance) of the used conductor.

Referring to FIG. 21, electric current travelling beneath or at thesurface of the conductor (Skin-Effect) is shown.

It is also widely assumed that when passing through alternating current(like a radio frequency signal) through a conductor that the signal ispassing through the skin layers of the conductor, called the SkinEffect. The chosen frequency of the alternating current defines the“Location/position” and “depth” of the Skin Effect. At high frequenciesthe electrical current will travel right at or near the surface of theconductor (A) while at lower frequencies (in the 5 to 10 Hz regions fora 20 mm diameter SH) the electrical alternating current will penetratemore the centre of the shafts cross section (E). Also, the relativecurrent density is higher in the current occupied regions at higher ACfrequencies in comparison to the relative current density near thecentre of the shaft at very low AC frequencies (as there is more spaceavailable for the current to flow through).

Referring to FIG. 22, the electrical current density of an electricalconductor (cross-section 90 deg to the current flow) when passingthrough the conductor an alternating current at different frequencies isillustrated.

The desired magnetic field design of the PCME sensor technology are twocircular magnetic field structures, stored in two layers on top of eachother (“Picky-Back”), and running in opposite direction to each other(Counter-Circular).

Again referring to FIG. 13, a desired magnetic sensor structure isshown: two endless magnetic loops placed on top of each other, runningin opposite directions to each other: Counter-Circular “Picky-Back”Field Design.

To make this magnetic field design highly sensitive to mechanicalstresses that will be applied to the SH (shaft), and to generate thelargest sensor signal possible, the desired magnetic field structure hasto be placed nearest to the shaft surface. Placing the circular magneticfields to close to the centre of the SH will cause damping of the useravailable sensor-output-signal slope (most of the sensor signal willtravel through the Ferro-magnetic shaft material as it has a much higherpermeability in comparison to air), and increases the non-uniformity ofthe sensor signal (in relation to shaft rotation and to axial movementsof the shaft in relation to the secondary sensor.

Referring to FIG. 23, magnetic field structures stored near the shaftsurface and stored near the centre of the shaft are illustrated.

It may be difficult to achieve the desired permanent magnetic encodingof the SH when using AC (alternating current) as the polarity of thecreated magnetic field is constantly changing and therefore may act moreas a Degaussing system.

The PCME technology requires that a strong electrical current(“uni-polar” or DC, to prevent erasing of the desired magnetic fieldstructure) is travelling right below the shaft surface (to ensure thatthe sensor signal will be uniform and measurable at the outside of theshaft). In addition a Counter-Circular, “picky back” magnetic fieldstructure needs to be formed.

It is possible to place the two Counter-Circular magnetic fieldstructures in the shaft by storing them into the shaft one after eachother. First the inner layer will be stored in the SH, and then theouter layer by using a weaker magnetic force (preventing that the innerlayer will be neutralized and deleted by accident. To achieve this, theknown “permanent” magnet encoding techniques can be applied as describedin patents from FAST technology, or by using a combination of electricalcurrent encoding and the “permanent” magnet encoding.

A much simpler and faster encoding process uses “only” electric currentto achieve the desired Counter-Circular “Picky-Back” magnetic fieldstructure. The most challenging part here is to generate theCounter-Circular magnetic field.

A uniform electrical current will produce a uniform magnetic field,running around the electrical conductor in a 90 deg angle, in relationto the current direction (A). When placing two conductors side-by-side(B) then the magnetic field between the two conductors seems tocancel-out the effect of each other (C). Although still present, thereis no detectable (or measurable) magnetic field between the closelyplaced two conductors. When placing a number of electrical conductorsside-by-side (D) the “measurable” magnetic field seems to go around theoutside the surface of the “flat” shaped conductor.

Referring to FIG. 24, the magnetic effects when looking at thecross-section of a conductor with a uniform current flowing through themare shown.

The “flat” or rectangle shaped conductor has now been bent into a“U”-shape. When passing an electrical current through the “U”-shapedconductor then the magnetic field following the outer dimensions of the“U”-shape is cancelling out the measurable effects in the inner halve ofthe “U”.

Referring to FIG. 25, the zone inside the “U”-shaped conductor seem tobe magnetically “Neutral” when an electrical current is flowing throughthe conductor.

When no mechanical stress is applied to the cross-section of a“U”-shaped conductor it seems that there is no magnetic field presentinside of the “U” (F). But when bending or twisting the “U”-shapedconductor the magnetic field will no longer follow its original path (90deg angle to the current flow). Depending on the applied mechanicalforces, the magnetic field begins to change slightly its path. At thattime the magnetic-field-vector that is caused by the mechanical stresscan be sensed and measured at the surface of the conductor, inside andoutside of the “U”-shape. Note: This phenomena is applies only at veryspecific electrical current levels.

The same applies to the “O”-shaped conductor design. When passing auniform electrical current through an “O”-shaped conductor (Tube) themeasurable magnetic effects inside of the “O” (Tube) have cancelled-outeach other (G).

Referring to FIG. 26, the zone inside the “O”-shaped conductor seem tobe magnetically “Neutral” when an electrical current is flowing throughthe conductor.

However, when mechanical stresses are applied to the “O”-shapedconductor (Tube) it becomes evident that there has been a magnetic fieldpresent at the inner side of the “O”-shaped conductor. The inner,counter directional magnetic field (as well as the outer magnetic field)begins to tilt in relation to the applied torque stresses. This tiltingfield can be clearly sensed and measured.

In the following, an Encoding Pulse Design will be described.

To achieve the desired magnetic field structure (Counter-Circular,Picky-Back, Fields Design) inside the SH, according to an exemplaryembodiment of a method of the present invention, unipolar electricalcurrent pulses are passed through the Shaft (or SH). By using “pulses”the desired “Skin-Effect” can be achieved. By using a “unipolar” currentdirection (not changing the direction of the electrical current) thegenerated magnetic effect will not be erased accidentally.

The used current pulse shape is most critical to achieve the desiredPCME sensor design. Each parameter has to be accurately and repeatablecontrolled: Current raising time, Constant current on-time, Maximalcurrent amplitude, and Current falling time. In addition it is verycritical that the current enters and exits very uniformly around theentire shaft surface.

In the following, a Rectangle Current Pulse Shape will be described.

Referring to FIG. 27, a rectangle shaped electrical current pulse isillustrated.

A rectangle shaped current pulse has a fast raising positive edge and afast falling current edge. When passing a rectangle shaped current pulsethrough the SH, the raising edge is responsible for forming the targetedmagnetic structure of the PCME sensor while the flat “on” time and thefalling edge of the rectangle shaped current pulse are counterproductive.

Referring to FIG. 28, a relationship between rectangles shaped CurrentEncoding Pulse-Width (Constant Current On-Time) and Sensor Output SignalSlope is shown.

In the following example a rectangle shaped current pulse has been usedto generate and store the Couter-Circilar “Picky-Back” field in a 15 mmdiameter, 14CrNi14 shaft. The pulsed electric current had its maximum ataround 270 Ampere. The pulse “on-time” has been electronicallycontrolled. Because of the high frequency component in the rising andfalling edge of the encoding pulse, this experiment can not trulyrepresent the effects of a true DC encoding SH. Therefore theSensor-Output-Signal Slope-curve eventually flattens-out at above 20mV/Nm when passing the Constant-Current On-Time of 1000 ms.

Without using a fast raising current-pulse edge (like using a controlledramping slope) the sensor output signal slope would have been very poor(below 10 mV/Nm). Note: In this experiment (using 14CrNi14) the signalhysteresis was around 0.95% of the FS signal (FS=75 Nm torque).

Referring to FIG. 29, increasing the Sensor-Output Signal-Slope by usingseveral rectangle shaped current pulses in succession is shown.

The Sensor-Output-Signal slope can be improved when using severalrectangle shaped current-encoding-pulses in successions. In comparisonsto other encoding-pulse-shapes the fast falling current-pulse signalslope of the rectangle shaped current pulse will prevent that theSensor-Output-Signal slope may ever reach an optimal performance level.Meaning that after only a few current pulses (2 to 10) have been appliedto the SH (or Shaft) the Sensor-Output Signal-Slope will no longer rise.

In the following, a Discharge Current Pulse Shape is described.

The Discharge-Current-Pulse has no Constant-Current ON-Time and has nofast falling edge. Therefore the primary and most felt effect in themagnetic encoding of the SH is the fast raising edge of this currentpulse type.

As shown in FIG. 30, a sharp raising current edge and a typicaldischarging curve provides best results when creating a PCME sensor.

Referring to FIG. 31, a PCME Sensor-Output Signal-Slope optimization byidentifying the right pulse current is illustrated.

At the very low end of the pulse current scale (0 to 75 A for a 15 mmdiameter shaft, 14CrNi14 shaft material) the “Discharge-Current-Pulsetype is not powerful enough to cross the magnetic threshold needed tocreate a lasting magnetic field inside the Ferro magnetic shaft. Whenincreasing the pulse current amplitude the double circular magneticfield structure begins to form below the shaft surface. As the pulsecurrent amplitude increases so does the achievable torque sensor-outputsignal-amplitude of the secondary sensor system. At around 400 A to 425A the optimal PCME sensor design has been achieved (the two counterflowing magnetic regions have reached their most optimal distance toeach other and the correct flux density for best sensor performances.

Referring to FIG. 32, Sensor Host (SH) cross section with the optimalPCME electrical current density and location during the encoding pulseis illustrated.

When increasing further the pulse current amplitude the absolute, torqueforce related, sensor signal amplitude will further increase (curve 2)for some time while the overall PCME-typical sensor performances willdecrease (curve 1). When passing 900 A Pulse Current Amplitude (for a 15mm diameter shaft) the absolute, torque force related, sensor signalamplitude will begin to drop as well (curve 2) while the PCME sensorperformances are now very poor (curve 1).

Referring to FIG. 33, Sensor Host (SH) cross sections and the electricalpulse current density at different and increasing pulse current levelsis shown.

As the electrical current occupies a larger cross section in the SH thespacing between the inner circular region and the outer (near the shaftsurface) circular region becomes larger.

Referring to FIG. 34, better PCME sensor performances will be achievedwhen the spacing between the Counter-Circular “Picky-Back” Field designis narrow (A).

The desired double, counter flow, circular magnetic field structure willbe less able to create a close loop structure under torque forces whichresults in a decreasing secondary sensor signal amplitude.

Referring to FIG. 35, flattening-out the current-discharge curve willalso increase the Sensor-Output Signal-Slope.

When increasing the Current-Pulse discharge time (making the currentpulse wider) (B) the Sensor-Output Signal-Slope will increase. Howeverthe required amount of current is very high to reduce the slope of thefalling edge of the current pulse. It might be more practical to use acombination of a high current amplitude (with the optimal value) and theslowest possible discharge time to achieve the highest possibleSensor-Output Signal Slope.

In the following, Electrical Connection Devices in the frame of PrimarySensor Processing will be described.

The PCME technology (it has to be noted that the term ‘PCME’ technologyis used to refer to exemplary embodiments of the present invention)relies on passing through the shaft very high amounts of pulse-modulatedelectrical current at the location where the Primary Sensor should beproduced. When the surface of the shaft is very clean and highlyconductive a multi-point Copper or Gold connection may be sufficient toachieve the desired sensor signal uniformity. Important is that theImpedance is identical of each connection point to the shaft surface.This can be best achieved when assuring the cable length (L) isidentical before it joins the main current connection point (I).

Referring to FIG. 36, a simple electrical multi-point connection to theshaft surface is illustrated.

However, in most cases a reliable and repeatable multi-point electricalconnection can be only achieved by ensuring that the impedance at eachconnection point is identical and constant. Using a spring pushed,sharpened connector will penetrate possible oxidation or isolationlayers (may be caused by finger prints) at the shaft surface.

Referring to FIG. 37, a multi channel, electrical connecting fixture,with spring loaded contact points is illustrated.

When processing the shaft it is most important that the electricalcurrent is injected and extracted from the shaft in the most uniform waypossible. The above drawing shows several electrical, from each otherinsulated, connectors that are held by a fixture around the shaft. Thisdevice is called a Shaft-Processing-Holding-Clamp (or SPHC). The numberof electrical connectors required in a SPHC depends on the shafts outerdiameter. The larger the outer diameter, the more connectors arerequired. The spacing between the electrical conductors has to beidentical from one connecting point to the next connecting point. Thismethod is called Symmetrical-“Spot”-Contacts.

Referring to FIG. 38, it is illustrated that increasing the number ofelectrical connection points will assist the efforts of entering andexiting the Pulse-Modulated electrical current. It will also increasethe complexity of the required electronic control system.

Referring to FIG. 39, an example of how to open the SPHC for easy shaftloading is shown.

In the following, an encoding scheme in the frame of Primary SensorProcessing will be described.

The encoding of the primary shaft can be done by using permanent magnetsapplied at a rotating shaft or using electric currents passing throughthe desired section of the shaft. When using permanent magnets a verycomplex, sequential procedure is necessary to put the two layers ofclosed loop magnetic fields, on top of each other, in the shaft. Whenusing the PCME procedure the electric current has to enter the shaft andexit the shaft in the most symmetrical way possible to achieve thedesired performances.

Referring to FIG. 40, two SPHCs (Shaft Processing Holding Clamps) areplaced at the borders of the planned sensing encoding region. Throughone SPHC the pulsed electrical current (I) will enter the shaft, whileat the second SPHC the pulsed electrical current (I) will exit theshaft. The region between the two SPHCs will then turn into the primarysensor.

This particular sensor process will produce a Single Field (SF) encodedregion. One benefit of this design (in comparison to those that aredescribed below) is that this design is insensitive to any axial shaftmovements in relation to the location of the secondary sensor devices.The disadvantage of this design is that when using axial (or in-line)placed MFS coils the system will be sensitive to magnetic stray fields(like the earth magnetic field).

Referring to FIG. 41, a Dual Field (DF) encoded region (meaning twoindependent functioning sensor regions with opposite polarity,side-by-side) allows cancelling the effects of uniform magnetic strayfields when using axial (or in-line) placed MFS coils. However, thisprimary sensor design also shortens the tolerable range of shaftmovement in axial direction (in relation to the location of the MFScoils). There are two ways to produce a Dual Field (DF) encoded regionwith the PCME technology. The sequential process, where the magneticencoded sections are produced one after each other, and the parallelprocess, where both magnetic encoded sections are produced at the sametime.

The first process step of the sequential dual field design is tomagnetically encode one sensor section (identically to the Single Fieldprocedure), whereby the spacing between the two SPHC has to be halve ofthe desired final length of the Primary Sensor region. To simplify theexplanations of this process we call the SPHC that is placed in thecentre of the final Primary Sensor Region the Centre SPHC (C-SPHC), andthe SPHC that is located at the left side of the Centre SPHC: L-SPHC.

Referring to FIG. 42, the second process step of the sequential DualField encoding will use the SPHC that is located in the centre of thePrimary Sensor region (called C-SPHC) and a second SPHC that is placedat the other side (the right side) of the centre SPHC, called R-SPHC.Important is that the current flow direction in the centre SPHC (C-SPHC)is identical at both process steps.

Referring to FIG. 43, the performance of the final Primary Sensor Regiondepends on how close the two encoded regions can be placed in relationto each other. And this is dependent on the design of the used centreSPHC. The narrower the in-line space contact dimensions are of theC-SPHC, the better are the performances of the Dual Field PCME sensor.

FIG. 44 shows the pulse application according to another exemplaryembodiment of the present invention. As my be taken from the abovedrawing, the pulse is applied to three locations of the shaft. Due tothe current distribution to both sides of the middle electrode where thecurrent I is entered into the shaft, the current leaving the shaft atthe lateral electrodes is only half the current entered at the middleelectrode, namely ½I. The electrodes are depicted as rings whichdimensions are adapted to the dimensions of the outer surface of theshaft. However, it has to be noted that other electrodes may be used,such as the electrodes comprising a plurality of pin electrodesdescribed later in this text.

Referring to FIG. 45, magnetic flux directions of the two sensorsections of a Dual Field PCME sensor design are shown when no torque orlinear motion stress is applied to the shaft. The counter flow magneticflux loops do not interact with each other.

Referring to FIG. 46, when torque forces or linear stress forces areapplied in a particular direction then the magnetic flux loops begin torun with an increasing tilting angle inside the shaft. When the tiltedmagnetic flux reaches the PCME segment boundary then the flux lineinteracts with the counterflowing magnetic flux lines, as shown.

Referring to FIG. 47, when the applied torque direction is changing (forexample from clock-wise to counter-clock-wise) so will change thetilting angle of the counterflow magnetic flux structures inside the PCMEncoded shaft.

In the following, a Multi Channel Current Driver for Shaft Processingwill be described.

In cases where an absolute identical impedance of the current path tothe shaft surface can not be guaranteed, then electric currentcontrolled driver stages can be used to overcome this problem.

Referring to FIG. 48, a six-channel synchronized Pulse current driversystem for small diameter Sensor Hosts (SH) is shown. As the shaftdiameter increases so will the number of current driver channels.

In the following, Bras Ring Contacts and Symmetrical “Spot” Contactswill be described.

When the shaft diameter is relative small and the shaft surface is cleanand free from any oxidations at the desired Sensing Region, then asimple “Bras”-ring (or Copper-ring) contact method can be chosen toprocess the Primary Sensor.

Referring to FIG. 49, bras-rings (or Copper-rings) tightly fitted to theshaft surface may be used, with solder connections for the electricalwires. The area between the two Bras-rings (Copper-rings) is the encodedregion.

However, it is very likely that the achievable RSU performances are muchlower then when using the Symmetrical “Spot” Contact method.

In the following, a Hot-Spotting concept will be described.

A standard single field (SF) PCME sensor has very poor Hot-Spottingperformances. The external magnetic flux profile of the SF PCME sensorsegment (when torque is applied) is very sensitive to possible changes(in relation to Ferro magnetic material) in the nearby environment. Asthe magnetic boundaries of the SF encoded sensor segment are not welldefined (not “Pinned Down”) they can “extend” towards the directionwhere Ferro magnet material is placed near the PCME sensing region.

Referring to FIG. 50, a PCME process magnetized sensing region is verysensitive to Ferro magnetic materials that may come close to theboundaries of the sensing regions.

To reduce the Hot-Spotting sensor sensitivity the PCME sensor segmentboundaries have to be better defined by pinning them down (they can nolonger move).

Referring to FIG. 51, a PCME processed Sensing region with two “PinningField Regions” is shown, one on each side of the Sensing Region.

By placing Pinning Regions closely on either side the Sensing Region,the Sensing Region Boundary has been pinned down to a very specificlocation. When Ferro magnetic material is coming close to the SensingRegion, it may have an effect on the outer boundaries of the PinningRegions, but it will have very limited effects on the Sensing RegionBoundaries.

There are a number of different ways, according to exemplary embodimentsof the present invention how the SH (Sensor Host) can be processed toget a Single Field (SF) Sensing Region and two Pinning Regions, one oneach side of the Sensing Region. Either each region is processed aftereach other (Sequential Processing) or two or three regions are processedsimultaneously (Parallel Processing). The Parallel Processing provides amore uniform sensor (reduced parasitic fields) but requires much higherlevels of electrical current to get to the targeted sensor signal slope.

Referring to FIG. 52, a parallel processing example for a Single Field(SF) PCME sensor with Pinning Regions on either side of the main sensingregion is illustrated, in order to reduce (or even eliminate)Hot-Spotting.

A Dual Field PCME Sensor is less sensitive to the effects ofHot-Spotting as the sensor centre region is already Pinned-Down.However, the remaining Hot-Spotting sensitivity can be further reducedby placing Pinning Regions on either side of the Dual-Field SensorRegion.

Referring to FIG. 53, a Dual Field (DF) PCME sensor with Pinning Regionseither side is shown.

When Pinning Regions are not allowed or possible (example: limited axialspacing available) then the Sensing Region has to be magneticallyshielded from the influences of external Ferro Magnetic Materials.

In the following, the Rotational Signal Uniformity (RSU) will beexplained.

The RSU sensor performance are, according to current understanding,mainly depending on how circumferentially uniform the electrical currententered and exited the SH surface, and the physical space between theelectrical current entry and exit points. The larger the spacing betweenthe current entry and exit points, the better is the RSU performance.

Referring to FIG. 54, when the spacings between the individualcircumferential placed current entry points are relatively large inrelation to the shaft diameter (and equally large are the spacingsbetween the circumferentially placed current exit points) then this willresult in very poor RSU performances. In such a case the length of thePCM Encoding Segment has to be as large as possible as otherwise thecreated magnetic field will be circumferentially non-uniform.

Referring to FIG. 55, by widening the PCM Encoding Segment thecircumferentially magnetic field distribution will become more uniform(and eventually almost perfect) at the halve distance between thecurrent entry and current exit points. Therefore the RSU performance ofthe PCME sensor is best at the halve way-point between of thecurrent-entry/current-exit points.

Next, the basic design issues of a NCT sensor system will be described.

Without going into the specific details of the PCM-Encoding technology,the end-user of this sensing technology need to now some design detailsthat will allow him to apply and to use this sensing concept in hisapplication. The following pages describe the basic elements of amagnetostriction based NCT sensor (like the primary sensor, secondarysensor, and the SCSP electronics), what the individual components looklike, and what choices need to be made when integrating this technologyinto an already existing product.

In principle the PCME sensing technology can be used to produce astand-alone sensor product. However, in already existing industrialapplications there is little to none space available for a “stand-alone”product. The PCME technology can be applied in an existing productwithout the need of redesigning the final product.

In case a stand-alone torque sensor device or position detecting sensordevice will be applied to a motor-transmission system it may requirethat the entire system need to undergo a major design change.

In the following, referring to FIG. 56, a possible location of a PCMEsensor at the shaft of an engine is illustrated.

FIG. 56 shows possible arrangement locations for the torque sensoraccording to an exemplary embodiment of the present invention, forexample, in a gear box of a motorcar. The upper portion of FIG. 56 showsthe arrangement of the PCME torque sensor according to an exemplaryembodiment of the present invention. The lower portion of the FIG. 56shows the arrangement of a stand alone sensor device which is notintegrated in the input shaft of the gear box as is in the exemplaryembodiment of the present invention.

As may be taken from the upper portion of FIG. 56, the torque sensoraccording to an exemplary embodiment of the present invention may beintegrated into the input shaft of the gear box. In other words, theprimary sensor may be a portion of the input shaft. In other words, theinput shaft may be magnetically encoded such that it becomes the primarysensor or sensor element itself. The secondary sensors, i.e. the coils,may, for example, be accommodated in a bearing portion close to theencoded region of the input shaft. Due to this, for providing the torquesensor between the power source and the gear box, it is not necessary tointerrupt the input shaft and to provide a separate torque sensor inbetween a shaft going to the motor and another shaft going to the gearbox as shown in the lower portion of FIG. 56.

Due to the integration of the encoded region in the input shaft it ispossible to provide for a torque sensor without making any alterationsto the input shaft, for example, for a car. This may be important, forexample, in parts for an aircraft where each part has to undergoextensive tests before being allowed for use in the aircraft. Suchtorque sensor according to the present invention may be perhaps evenwithout such extensive testing being corporated in shafts in aircraft orturbine since, the immediate shaft is not altered. Also, no materialeffects are caused to the material of the shaft.

Furthermore, as may be taken from FIG. 56, the torque sensor accordingto an exemplary embodiment of the present invention may allow to reducea distance between a gear box and a power source since the provision ofa separate stand alone torque sensor between the shaft exiting the powersource and the input shaft to the gear box becomes obvious.

Next, Sensor Components will be explained.

A non-contact magnetostriction sensor (NCT-Sensor), as shown in FIG. 57,may consist, according to an exemplary embodiment of the presentinvention, of three main functional elements: The Primary Sensor, theSecondary Sensor, and the Signal Conditioning & Signal Processing (SCSP)electronics.

Depending on the application type (volume and quality demands, targetedmanufacturing cost, manufacturing process flow) the customer can choseto purchase either the individual components to build the sensor systemunder his own management, or can subcontract the production of theindividual modules.

FIG. 58 shows a schematic illustration of components of a non-contacttorque sensing device. However, these components can also be implementedin a non-contact position sensing device.

In cases where the annual production target is in the thousands of unitsit may be more efficient to integrate the “primary-sensormagnetic-encoding-process” into the customers manufacturing process. Insuch a case the customer needs to purchase application specific“magnetic encoding equipment”.

In high volume applications, where cost and the integrity of themanufacturing process are critical, it is typical that NCTE suppliesonly the individual basic components and equipment necessary to build anon-contact sensor:

-   -   ICs (surface mount packaged, Application-Specific Electronic        Circuits)    -   MFS-Coils (as part of the Secondary Sensor)    -   Sensor Host Encoding Equipment (to apply the magnetic encoding        on the shaft=Primary Sensor)

Depending on the required volume, the MFS-Coils can be supplied alreadyassembled on a frame, and if desired, electrically attached to a wireharness with connector. Equally the SCSP (Signal Conditioning & SignalProcessing) electronics can be supplied fully functional in PCB format,with or without the MFS-Coils embedded in the PCB.

FIG. 59 shows components of a sensing device.

As can be seen from FIG. 60, the number of required MFS-coils isdependent on the expected sensor performance and the mechanicaltolerances of the physical sensor design. In a well designed sensorsystem with perfect Sensor Host (SH or magnetically encoded shaft) andminimal interferences from unwanted magnetic stray fields, only 2MFS-coils are needed. However, if the SH is moving radial or axial inrelation to the secondary sensor position by more than a few tenths of amillimeter, then the number of MFS-coils need to be increased to achievethe desired sensor performance.

In the following, a control and/or evaluation circuitry will beexplained.

The SCSP electronics, according to an exemplary embodiment of thepresent invention, consist of the NCTE specific ICs, a number ofexternal passive and active electronic circuits, the printed circuitboard (PCB), and the SCSP housing or casing. Depending on theenvironment where the SCSP unit will be used the casing has to be sealedappropriately.

Depending on the application specific requirements NCTE (according to anexemplary embodiment of the present invention) offers a number ofdifferent application specific circuits:

-   -   Basic Circuit    -   Basic Circuit with integrated Voltage Regulator    -   High Signal Bandwidth Circuit    -   Optional High Voltage and Short Circuit Protection Device    -   Optional Fault Detection Circuit

FIG. 61 shows a single channel, low cost sensor electronics solution.

As may be taken from FIG. 61, there may be provided a secondary sensorunit which comprises, for example, coils. These coils are arranged as,for example, shown in FIG. 60 for sensing variations in a magnetic fieldemitted from the primary sensor unit, i.e. the sensor shaft or sensorelement when torque is applied thereto. The secondary sensor unit isconnected to a basis IC in a SCST. The basic IC is connected via avoltage regulator to a positive supply voltage. The basic IC is alsoconnected to ground. The basic IC is adapted to provide an analog outputto the outside of the SCST which output corresponds to the variation ofthe magnetic field caused by the stress applied to the sensor element.

FIG. 62 shows a dual channel, short circuit protected system design withintegrated fault detection. This design consists of 5 ASIC devices andprovides a high degree of system safety. The Fault-Detection ICidentifies when there is a wire breakage anywhere in the sensor system,a fault with the MFS coils, or a fault in the electronic driver stagesof the “Basic IC”.

Next, the Secondary Sensor Unit will be explained.

The Secondary Sensor may, according to one embodiment shown in FIG. 63,consist of the elements: One to eight MFS (Magnetic Field Sensor) Coils,the Alignment- & Connection-Plate, the wire harness with connector, andthe Secondary-Sensor-Housing.

The MFS-coils may be mounted onto the Alignment-Plate. Usually theAlignment-Plate allows that the two connection wires of each MFS-Coilare soldered/connected in the appropriate way. The wire harness isconnected to the alignment plate. This, completely assembled with theMFS-Coils and wire harness, is then embedded or held by theSecondary-Sensor-Housing.

The main element of the MFS-Coil is the core wire, which has to be madeout of an amorphous-like material.

Depending on the environment where the Secondary-Sensor-Unit will beused, the assembled Alignment Plate has to be covered by protectivematerial. This material can not cause mechanical stress or pressure onthe MFS-coils when the ambient temperature is changing.

In applications where the operating temperature will not exceed +110 degC. the customer has the option to place the SCSP electronics (ASIC)inside the secondary sensor unit (SSU). While the ASIC devices canoperated at temperatures above +125 deg C. it will become increasinglymore difficult to compensate the temperature related signal-offset andsignal-gain changes.

The recommended maximal cable length between the MFS-coils and the SCSPelectronics is 2 meters. When using the appropriate connecting cable,distances of up to 10 meters are achievable. To avoid signal-cross-talkin multi-channel applications (two independent SSUs operating at thesame Primary Sensor location=Redundant Sensor Function), speciallyshielded cable between the SSUs and the SCSP Electronics should beconsidered.

When planning to produce the Secondary-Sensor-Unit (SSU) the producerhas to decide which part/parts of the SSU have to be purchased throughsubcontracting and which manufacturing steps will be made in-house.

In the following, Secondary Sensor Unit Manufacturing Options will bedescribed.

When integrating the NCT-Sensor into a customized tool or standardtransmission system then the systems manufacturer has several options tochoose from:

-   -   custom made SSU (including the wire harness and connector)    -   selected modules or components; the final SSU assembly and        system test may be done under the customer's management.    -   only the essential components (MFS-coils or MFS-core-wire,        Application specific ICs) and will produce the SSU in-house.

FIG. 64 illustrates an exemplary embodiment of a Secondary Sensor UnitAssembly.

Next, a Primary Sensor Design is explained.

The SSU (Secondary Sensor Units) can be placed outside the magneticallyencoded SH (Sensor Host) or, in case the SH is hollow, inside the SH.The achievable sensor signal amplitude is of equal strength but has amuch better signal-to-noise performance when placed inside the hollowshaft.

FIG. 65 illustrates two configurations of the geometrical arrangement ofPrimary Sensor and Secondary Sensor.

Improved sensor performances may be achieved when the magnetic encodingprocess is applied to a straight and parallel section of the SH (shaft).For a shaft with 15 mm to 25 mm diameter the optimal minimum length ofthe Magnetically Encoded Region is 25 mm. The sensor performances willfurther improve if the region can be made as long as 45 mm (adding GuardRegions). In complex and highly integrated transmission (gearbox)systems it will be difficult to find such space. Under more idealcircumstances, the Magnetically Encoding Region can be as short as 14min, but this bears the risk that not all of the desired sensorperformances can be achieved.

As illustrated in FIG. 66, the spacing between the SSU (Secondary SensorUnit) and the Sensor Host surface, according to an exemplary embodimentof the present invention, should be held as small as possible to achievethe best possible signal quality.

Next, the Primary Sensor Encoding Equipment will be described.

An example is shown in FIG. 67.

Depending on which magnetostriction sensing technology will be chosen,the Sensor Host (SH) needs to be processed and treated accordingly. Thetechnologies vary by a great deal from each other (ABB, FAST, FT,Kubota, MDI, NCTE, RM, Siemens, . . . ) and so does the processingequipment required. Some of the available magnetostriction sensingtechnologies do not need any physical changes to be made on the SH andrely only on magnetic processing (MDI, FAST, NCTE).

While the MDI technology is a two phase process, the FAST technology isa three phase process, and the NCTE technology a one phase process,called PCM Encoding.

One should be aware that after the magnetic processing, the Sensor Host(SH or Shaft), has become a “precision measurement” device and has to betreated accordingly. The magnetic processing should be the very laststep before the treated SH is carefully placed in its final location.

The magnetic processing should be an integral part of the customer'sproduction process (in-house magnetic processing) under the followingcircumstances:

-   -   High production quantities (like in the thousands)    -   Heavy or difficult to handle SH (e.g. high shipping costs)    -   Very specific quality and inspection demands (e.g. defense        applications)

In all other cases it may be more cost effective to get the SHmagnetically treated by a qualified and authorized subcontractor, suchas NCTE. For the “in-house” magnetic processing dedicated manufacturingequipment is required. Such equipment can be operated fully manually,semi-automated, and fully automated. Depending on the complexity andautomation level the equipment can cost anywhere from EUR 20 k to aboveEUR 500 k.

In the following, referring to FIG. 68, a position sensor array 100according to a first embodiment of the invention will be described.

The position sensor array 100 comprises a reciprocating shaft 101 drivenby a motor (not shown in FIG. 68), wherein the reciprocating shaft 101reciprocates along a reciprocation direction 102. Further, the positionsensor array 100 comprises a position sensor device for determining aposition of the reciprocating shaft 101. The position sensor device fordetermining a position of the reciprocating shaft 101 comprises onemagnetically encoded region 103 integrated in a surface region of thereciprocating shaft 101. Further, the position sensor device comprisesone detection coil 104, a measuring unit 105 for measuring a magneticfield based on the electrical signals provided by the detection coil104, and a determining unit 106. The detection coil 104 is adapted todetect a signal generated by the magnetically encoded region 103 whenthe magnetically encoded region 103 reciprocating with the reciprocatingshaft 101 passes a surrounding area of the detection coil 104. In thissurrounding area, a present magnetic element can be detected by thedetection coil 104. The determining unit 106 is adapted to determine theposition of the reciprocating shaft 101 based on the detected signal,which is measured by a measuring unit 105 coupled with the detectioncoil 104.

The magnetically encoded region 103 is realized according to the PCMEtechnology described above. Therefore, the magnetically encoded region103 is a permanent magnetic region having a circumferentially magnetizedregion of the reciprocating shaft 101 made from industrial steel. Themagnetically encoded region 103 is formed by a first magnetic flowregion oriented in a first direction and by a second magnetic flowregion oriented in a second direction, wherein the first direction isopposite to the second direction. In a cross-sectional view of thecylindrical reciprocating shaft 101 perpendicular to the paper plane ofFIG. 68 and perpendicular to the reciprocating direction 102 of thereciprocating shaft 101, there is a first circular magnetic flow havingthe first direction and a first radius and the second circular magneticflow having the second direction and a second radius, wherein the firstradius is larger than the second radius.

When the reciprocating shaft 101, driven by an engine which is not shownin FIG. 68, reciprocates along the reciprocation direction 102, i.e.oscillates along a direction 102 from left to right and vice versa, themagnetic flux through the detection coil 104 generated by themagnetically encoded region 103 varies with the time, since themagnetically encoded region 103 has a time dependent distance from thedetection coil 104. Thus, depending on the actual position of thereciprocating shaft 101, the induced voltage in the detection coil 104yielding a signal in the measuring unit 105, varies dependent of theactual position of the reciprocating shaft 101. Based on this measuredsignal, the determining unit 106 determines the actual position of thereciprocating shaft. The determining unit 106 provides this positioninformation to the control unit 107 which uses this information toregulate control signals for controlling the reciprocation of thereciprocating shaft 101.

In the following, referring to FIG. 69, a position sensor array 200according to a second embodiment of the invention will be described.

In contrast to the position sensor array 100, the position sensor array200 comprises a plurality of magnetically encoded regions divided in afirst group 201 of magnetically encoded regions and a second group 202of magnetically encoded regions which are provided at differentlocations on the reciprocating shaft 101.

Instead of the detection coil 104, the position sensor array 200comprises a first Hall-probe 203, a second Hall-probe 204 and thirdHall-probe 205 arranged along the reciprocating shaft 101. When thereciprocating shaft 101 reciprocates along a reciprocation direction102, the plurality of magnetically encoded regions 201, 202 pass theHall-probes 203 to 205 to produce a significant and unique timedependent signal pattern detected by the Hall-probes 203 to 205 andmeasured by the measuring unit 105, so that the determining unit 106 cancalculate the position of the reciprocating shaft 101 based on thesequence of signals.

Thus, the position sensor array 200 allows to sense the actual positionof the reciprocating shaft 101 on the basis of the PCME technology incascading sequence. The PCME encoding field group 201, 202 magneticallyencoded regions have a different length along the reciprocationdirection 102, whereby on one side of the reciprocating shaft 101 theshorter PCME encoding region 201 is placed and at the other end of theshaft 101 is the wider PCME encoding region 202.

The reciprocating shaft 101 is a hydraulic work cylinder. As can be seenfrom FIG. 69, the short magnetic position markers 201 are cascaded, andthe long magnetic position markers 202 are cascaded.

In the following, referring to FIG. 70, a position sensor array 300according to a third embodiment of the invention will be described.

The position sensor array 300 differs from the position sensor array 100in that a plurality of equal-width magnetically encoded regions 301 areprovided. Each of the magnetically encoded regions 301 has an equalwidth, l, along the reciprocating shaft 101. The magnetically encodedregions 301 are provided at different distances from one another, namelya distances of d, 2d, and 3d. In contrast to the horizontally aligneddetection coil 104 of FIG. 68, FIG. 70 shows a plurality of verticallyaligned detection coils 302 having their coil axis arranged verticallyaccording to the drawing of FIG. 70. The different distances betweenadjacent magnetically encoded regions and adjacent detection coils 302yield a time dependent pattern of signals generated in the detectioncoils 302 which allow to retrieve the actual position and velocity ofthe reciprocating shaft 101.

The arrangement of the coils 302 with respect to the magneticallyencoded regions 301 is symmetric, i.e. in a reference state of thereciprocating shaft 101 shown in FIG. 70, a central axis of each of thecoils 302 equals to a central axis of a corresponding one of themagnetically encoded regions 301.

In the following, referring to FIG. 71, a position sensor array 400according to a fourth embodiment of the invention will be described.

In the case of the position sensor array 400, a single horizontallyaligned detection coil 104 is provided, and three equal-widthmagnetically encoded regions 301. When the shaft 101 reciprocates alongdirection 102, a detection signal is detected by the horizontallyaligned detection coil 104 each time that one of the equal-widthmagnetically encoded regions 301 passes a close vicinity of thehorizontally aligned detection coil 104. Thus, a sequence of signals isdetected at the detection coil 104 which allows to recalculate theactual position of the shaft 101.

In the following, referring to FIG. 72, a position sensor array 500according to a fifth embodiment of the invention will be described.

The position sensor array 500 includes two ferromagnetic rings 501attached on different portions of the reciprocating shaft 101. Theseferromagnetic rings 501 made of iron material are separate ferromagneticelements which are attached on the reciprocating shaft 101 to formmagnetically encoded regions. Further, two horizontally aligneddetection coils 104 are provided to measure a time dependent magneticfield via an induction voltage which is generated in a respective one ofthe coils 104 when one of the ferromagnetic rings 501 passes one of thehorizontally aligned detection coils 104. As can be seen from thereference position of the reciprocating shaft 101 shown in FIG. 72, theferromagnetic rings 501 are provided at positions of the shaft 101 whichare non-symmetric with respect to the detection coils 104. In otherwords, in a configuration in which the position of the detection coil104 shown on the left hand side of FIG. 72 corresponds to the positionof the ferromagnetic ring 501 shown on the left hand side of FIG. 72,there is an offset between the position of the centre of the detectingcoil 104 shown on the right hand side of FIG. 72 and the position of thecentral axis of the ferromagnetic ring 501 shown on the right hand sideof FIG. 72. Consequently, the detection signals of the different coils104 are timely shifted with respect to each other. Such a time offsetyields further position information of the reciprocating shaft 101.

Referring to FIG. 73, a diagram 600 will be described showing a signalcurve 603 which can be detected by the coils 104 shown in FIG. 71 whenone of the magnetically encoded regions 301 passes the respective coil104. Along an abscissa 601 of diagram 600, the position x of thereciprocating shaft 101 is shown, and along an ordinate 602, a signalamplitude A(x) is shown. Thus, the signal curve 603 allows to determinethe position of the reciprocating shaft 101.

In the following, referring to FIG. 74, a position sensor array 700according to a sixth embodiment of the invention will be described. Incontrast to the position sensor array 100, the position sensor array 700shows an entirely magnetized shaft 701, i.e. a shaft which is entirelymade of ferromagnetic material or a shaft which is magnetized along itsentire length according to the PCME technology.

FIG. 75 shows a diagram 800 having an abscissa 801 along which theposition x of the entirely magnetized shaft 701 having a total length Lis shown. Along an ordinate 802 of diagram 800, the amplitude A(x) of asignal detected by the determining unit 106 is shown. Thus, the signalof FIG. 75 allows a unique identification of the actual position of theentirely magnetized shaft 701 of FIG. 74.

In the following, referring to FIG. 76, a position sensor array 900according to a seventh embodiment of the invention will be described.

In the case of the position sensor array 900, the reciprocating shaft101 is divided into a plurality of equally spaced first to fourthsegments 901 to 904. Each segment 901 to 904 comprises one magneticallyencoded region 301, the magnetically encoded regions 301 being arrangedin an asymmetric manner along the segments 901 to 904. The magneticallyencoded region 301 of the first segment 901 is arranged in the very leftpart, the magnetically encoded region 301 of the second segment 902 isarranged in the middle-left part, the magnetically encoded region 301 ofthe third segment 903 is arranged in the middle-right part and themagnetically encoded region 301 of the fourth segment 904 is arranged atthe very right part of the respective segment. Thus, the arrangement ofthe magnetically encoded regions 301 is shifted from segment to segment901 to 904. This yields a unique signal pattern detectable by the coils302 which allows an accurate estimation of the actual position of theshaft 101.

The equally spaced segments 901, 904 with different locations of themarkers 301 allow an estimation of the position of the reciprocatingshaft 101 by evaluating the signals detected by the coils 302.

In the following, referring to FIG. 77, a concrete processing apparatus1000 according to a first embodiment of the invention will be described.

The concrete processing apparatus 1000 is provided on a truck (notshown) equipped with a concrete mixer pump for mixing concrete materialusing a reciprocating shaft having the magnetic encoding of theinvention. Thus, a concrete pump is equipped with a hydraulically drivenwork cylinder, i.e. a reciprocating shaft. In order to securely controlthe function of the reciprocating shaft, the position of the shaftshould be known exactly. The invention provides a method of determiningthe exact position of the reciprocating cylinder of the concreteprocessing apparatus 1000.

FIG. 77 shows the concrete processing apparatus 1000 having a concreteprocessing chamber 1001 which includes an inlet 1003 for supplyingconcrete material 1005 in the concrete processing chamber 1001. Areciprocating work cylinder 1002 mixes the concrete material 1005 byreciprocating along a reciprocation direction 102 and transports theconcrete material 1005 to a concrete outlet 1004 connected to a pipeline(not shown) via which the concrete is supplied to a concrete consumer.

The reciprocating work cylinder 1002 has, on its reciprocating shaft,three magnetically encoded regions 301 manufactured according to thePCME technology. Sealing elements 1007 are provided to prevent anundesired mixture of concrete material 1005 with a hydraulic fluid 1006provided to drive the reciprocating work cylinder 1002. When themagnetically encoded regions 301 pass a detection coil 104, an inductionvoltage is generated in the coil 104 which is supplied to the measuringunit 105 and which allows the determining unit 106 to estimate thepresent position of the reciprocating work cylinder 1002. A positionindicating signal, in which the actual position of the cylinder 1002 isencoded, is provided to a control unit 107 which uses the positioninformation to optimize a driving control signal to drive thereciprocating work cylinder 1002.

Thus, the invention improves the quality of the generated concrete 1005and the operation of the reciprocating work cylinder 1002, by enablingan improved way of driving the work cylinder 1002 based on positioninformation of the cylinder 1002.

In the following, referring to FIG. 78, a concrete processing apparatus1100 according to a second embodiment of the invention will bedescribed.

FIG. 78 shows a twin cylinder pump arrangement having a first workingcylinder 1002 and a second work cylinder 1102 which allows a combinationof steady and gentle pumping patterns. Hydraulic oil 1006 is pumpedunder pressure to the working cylinders 1002, 1102. At one time, one ofthe working cylinders 1002, 1102 extends, while the other one retractsat the same time. Thus, one cylinder 1002, 1102 pumps and draws inconcrete material 1005, and the other cylinder 1102, 1002 pumps concretematerial 1005 into a connected pipeline (not shown). The assembly ofFIG. 78 is mounted on a truck to form a machine which is applicable inthe construction and civil engineering fields.

In contrast to the concrete processing apparatus 1000, two instead ofone work cylinders 1002, 1102 are provided in the case of the concreteprocessing apparatus 1100, namely the reciprocating work cylinder 1002and a further reciprocating work cylinder 1102. Moreover, a furtherconcrete inlet 1101 for supplying concrete material in a symmetricmanner is provided. Both of the reciprocating work cylinders 1002, 1102are hydraulically driven using the hydraulic fluid 1006.

According to the operation mode shown in FIG. 78, the reciprocating workcylinder 1002 moves along a first direction 1103, whereas the furtherreciprocating work cylinder 1102 moves along a second direction 1104which is opposite to the first direction 1103. A separation wall 1105separates the reciprocating work cylinders 1002, 1102 from each other.Along the shaft of each of the reciprocating cylinders 1002, 1102, aplurality of magnetic encoded regions 301 are provided which producemagnetic signals on coils 104. Each reciprocating cylinder 1002, 1102has assigned a pair of coils 104 having opposed coil axis, so that anevaluation of the signals generated in the coils 104 of each pair ofcoils allow to eliminate the influence of the magnetic field of theearth to further improve the accuracy of the detected positions.

In the following, further embodiments of the invention will be describedwhich may or may not be realized with PCME technology.

FIG. 79 and FIG. 80 show schematic views illustrating a sequence ofsignals 6810 captured by three magnetic field detectors 6800, 6801, 6802generated by six magnetic encoded regions (see “1” to “6”) provided with(from left to right) increasing distances from one another on areciprocating shaft (not shown) of a position sensor array according toan eighth embodiment of the invention. A first pickup location 6820 anda second pickup location 6830 are shown. The six magnetic encodedregions (markers) have the same physical dimension (width of the markersis constant), but the location in relation to each other is changing.

As can be seen from FIG. 80, when using three pickup modules 6800, 6801,6802, then the usable axial-measurement range is much larger than in ascenario of using one or two pickup modules, since there are no “dead”areas (at least two pickup devices have a usable signal at any givenlocation, at any point of time).

FIG. 81 and FIG. 82 show schematic views illustrating a sequence ofsignals 7000 captured by two magnetic field detectors 6800, 6801generated by six magnetic encoded regions (see “1” to “6”) provided with(from left to right) increasing distances from one another provided on areciprocating shaft (not shown) of a position sensor array according toa ninth embodiment of the invention.

When using two pickup devices 6800, 6801, the axial measurement rangeexpands considerably than when using only one pickup device. However,there are still “dead” areas 7100 between the markers where there is nosufficient information available through the pickup system. Apart fromthe “dead” areas 7100, the axial position can be determined accurately.Two pickups enable to determine accurately the axial position when twosignals are present at any given location.

FIG. 83 shows a schematic view illustrating a sequence of signals 6810captured by one magnetic field detector 6800 generated by six magneticencoded regions (see “1” to “6”) provided with (from left to right)increasing distances from one another provided on a reciprocating shaft(not shown) of a position sensor array according to a tenth embodimentof the invention. This embodiment allows to obtain axial positioninformation with low effort.

FIG. 84 to FIG. 86 show a hollow tube 7300 as reciprocating object withdifferent embodiments for magnetic encoded regions arranged inside thehollow tube. The magnetic field generated inside the tube 7300 has to bestrong enough to penetrate the outer tube wall.

According to the embodiment shown in FIG. 84, a permanent magnet 7301(synthetic magnet) is placed inside the tube.

According to the embodiment shown in FIG. 85, a coil 7400 (inductor) isplaced inside the tube which can be magnetized by an electrical powersource 7401.

According to the embodiment shown in FIG. 86, a helical coil 7500 isplaced inside the tube which can be magnetized by an electrical powersource 7401.

FIG. 87, FIG. 88 show a position sensor array 7600 according to aneleventh embodiment of the invention.

In an automatic automotive gearbox system, as shown in FIG. 87, FIG. 88,the position of the various tooth-wheels (gear-wheels) are changed bypush-pull-rods 7601. In a passenger car gearbox system may beparticularly four or more push-pull-rods 7601 to control the gearpositions of the cars transmission system. The push-pull-rods 7601 maybe operated by an electric or pneumatic or hydraulic actuator. Theactuators operate a hook 7602 which is inserted into a hole from thepush-pull-rod 7601.

The push-pull-rod may 7601 move as little as +/−10 mm (passenger cargearbox) or much more (truck gearbox). The optimal operation of thegearbox requires that the push-pull-rods 7601 are moved to precisepositions with little tolerances.

As the axial measurement range is relatively short (+/−10 mm, up to+/−20 mm) only one magnetic marker 103 is required for measuring theposition of the push-pull-rod 7601. The magnetic marker 103 can beplaced at any desired location of the push-pull-rod 7601 whereby thecross-section of the push-pull-rod 7601 where the marker 103 will beplaced can be round, square, rectangle, or any other desired shape. Asthe push-pull-rod 7601 does not rotate, a non-uniform (non-round) shapeof the rod's cross section is acceptable.

FIG. 87 shows a typical gearbox push-pull-rod 7601 design, required tochange the gear (tooth-wheel) position inside the gearbox by means of anexternally placed actuator. The actuator is attached to the hook 7602which is attached to the end of the push-pull-rod 7601.

FIG. 88 shows a detailed view of the push-pull-rod 7601 with an magneticmarker encoding 103 and at least one magnetic field detecting device104. The magnetic field detecting device 104 (example: coil) will detectthe exact axial (linear) position of the push-pull-rod 7601 in relationto the position of the magnetic field detecting device 104.

It should be noted that the term “comprising” does not exclude otherelements or steps and the “a” or “an” does not exclude a plurality. Alsoelements described in association with different embodiments may becombined.

1. A position sensor device for determining a position of areciprocating object, comprising: at least one magnetically encodedregion fixed on a reciprocating object; at least one magnetic fielddetector; a position determining unit; wherein the magnetic fielddetector is adapted to detect a signal generated by the magneticallyencoded region when the magnetically encoded region reciprocating withthe reciprocating object passes a surrounding area of the magnetic fielddetector; wherein the position determining unit is adapted to determinea position of a reciprocating object based on the detected magneticsignal.
 2. The position sensor device according to claim 1, wherein theat least one magnetically encoded region is a permanent magnetic region.3. The position sensor device according to claim 1, wherein the at leastone magnetically encoded region is a longitudinally magnetized region ofthe reciprocating object.
 4. The position sensor device according toclaim 1, wherein the at least one magnetically encoded region is acircumferentially magnetized region of the reciprocating object.
 5. Theposition sensor device according to claim 1, wherein the at least onemagnetically encoded region is formed by a first magnetic flow regionoriented in a first direction and by a second magnetic flow regionoriented in a second direction, and wherein the first direction isopposite to the second direction.
 6. The position sensor deviceaccording to claim 5, wherein, in a cross-sectional view of thereciprocating object, there is a first circular magnetic flow having thefirst direction and a first radius and a second circular magnetic flowhaving the second direction and a second radius, and wherein the firstradius is larger than the second radius.
 7. The position sensor deviceaccording to claim 1, wherein the at least one magnetically encodedregion is manufactured in accordance with the following manufacturingsteps: applying a first current pulse to a magnetizable element; whereinthe first current pulse is applied such that there is a first currentflow in a first direction along a longitudinal axis of the magnetizableelement; wherein the first current pulse is such that the application ofthe current pulse generates a magnetically encoded region in themagnetizable element.
 8. The position sensor device according to claim7, wherein a second current pulse is applied to the magnetizableelement; wherein the second current pulse is applied such that there isa second current flow in a second direction along the longitudinal axisof the magnetizable element.
 9. The position sensor device according toclaim 8, wherein each of the first and second current pulses has araising edge and a falling edge; wherein the raising edge is steeperthan the falling edge.
 10. The position sensor device according to claim8, wherein the first direction is opposite to the second direction. 11.The position sensor device according to claim 7, wherein themagnetizable element has a circumferential surface surrounding a coreregion of the magnetizable element; wherein the first current pulse isintroduced into the magnetizable element at a first location at thecircumferential surface such that there is the first current flow in thefirst direction in the core region of the magnetizable element; whereinthe first current pulse is discharged from the magnetizable element at asecond location at the circumferential surface; and wherein the secondlocation is at a distance in the first direction from the firstlocation.
 12. The position sensor device according to claim 8, whereinthe second current pulse is introduced into the magnetizable element atthe second location at the circumferential surface such that there isthe second current flow in the second direction in the core region ofthe magnetizable element; and wherein the second current pulse isdischarged from the magnetizable element at the first location at thecircumferential surface.
 13. (canceled)
 14. The position sensor deviceaccording to claim 1, wherein the at least one magnetically encodedregion is a magnetic element attached to the surface of thereciprocating object.
 15. The position sensor device according to claim1, wherein the at least one magnetic field detector comprises at leastone of the group consisting of a coil having a coil axis orientedessentially parallel to a reciprocating direction of the reciprocatingobject; a coil having a coil axis oriented essentially perpendicular toa reciprocating direction of the reciprocating object; a Hall-effectprobe; a Giant Magnetic Resonance magnetic field sensor; and a MagneticResonance magnetic field sensor.
 16. The position sensor deviceaccording to claim 1, further comprising: a plurality of magneticallyencoded regions fixed on the reciprocating object.
 17. The positionsensor device according to claim 16, wherein the plurality ofmagnetically encoded regions are arranged on the reciprocating object atconstant distances from one another.
 18. The position sensor deviceaccording to claim 16, wherein the plurality of magnetically encodedregions are arranged on the reciprocating object at different distancesfrom one another.
 19. (canceled)
 20. The position sensor deviceaccording to claim 16, wherein the plurality of magnetically encodedregions are arranged on the reciprocating object with constantdimensions.
 21. The position sensor device according to claim 16,wherein the plurality of magnetically encoded regions are arranged onthe reciprocating object with different dimensions.
 22. (canceled) 23.(canceled)
 24. The position sensor device according to claim 1, furthercomprising: a plurality of magnetic field detectors.
 25. The positionsensor device according to claim 24, wherein the plurality of magneticfield detectors are arranged along the reciprocating object at constantdistances from one another.
 26. The position sensor device according toclaim 24, wherein the plurality of magnetic field detectors are arrangedalong the reciprocating object at different distances from one another.27. The position sensor device according to claim 26, wherein thedifferent distances are selected as a function of one of a linearfunction, a logarithmic function and a power function.
 28. The positionsensor device according to claim 1, further comprising: a plurality ofmagnetically encoded regions fixed on the reciprocating object; and aplurality of magnetic field detectors.
 29. The position sensor deviceaccording to claim 28, wherein the arrangement of the plurality ofmagnetically encoded regions along the reciprocating object correspondsto the arrangement of the plurality of magnetic field detectors.
 30. Theposition sensor device according to claim 29, wherein at least a part ofthe plurality of magnetic field detectors are arranged displaced from anarrangement of a corresponding one of the plurality of magneticallyencoded regions arranged along the reciprocating object.
 31. Theposition sensor device according to claim 28, wherein a number of themagnetically encoded regions equals the number of magnetic fielddetectors.
 32. The position sensor device according to claim 27, whereina number of the magnetically encoded regions differs from the number ofmagnetic field detectors.
 33. The position sensor device according toclaim 1, wherein the reciprocating object is a push-pull-rod in agearbox of a vehicle.
 34. A position sensor array, comprising areciprocating object; and a position sensor device determining aposition of the reciprocating object, wherein the position sensor deviceincludes at least one magnetically encoded region fixed on areciprocating object, at least one magnetic field detector, and aposition determining unit, wherein the magnetic field detector isadapted to detect a signal generated by the magnetically encoded regionwhen the magnetically encoded region reciprocating with thereciprocating object passes a surrounding area of the magnetic fielddetector and wherein the position determining unit is adapted todetermine a position of a reciprocating object based on the detectedmagnetic signal.
 35. The position sensor array according to claim 34,wherein the reciprocating object is a shaft.
 36. The position sensorarray according to claim 34, wherein the magnetically encoded region isprovided along a part of a length of the reciprocating object.
 37. Theposition sensor array according to claim 34, wherein the magneticallyencoded region is provided along an entire length of the reciprocatingobject.
 38. The position sensor array according to claim 34, wherein thereciprocating object is divided into a plurality of equally spacedsegments, each segment comprising one magnetically encoded region, themagnetically encoded regions of the segments being arranged in anasymmetric manner.
 39. The position sensor array according to claim 34,further comprising: a control unit controlling a reciprocation of thereciprocating object based on the position of the reciprocating objectwhich is provided to the control unit by the position sensor device. 40.A concrete processing apparatus, comprising a concrete processingchamber; a reciprocating shaft arranged in the concrete processingchamber adapted to reciprocate to mix concrete; and a position sensordevice determining a position of the reciprocating shaft, wherein theposition sensor device includes at least one magnetically encoded regionfixed on a reciprocating object, at least one magnetic field detector,and a position determining unit, wherein the magnetic field detector isadapted to detect a signal generated by the magnetically encoded regionwhen the magnetically encoded region reciprocating with thereciprocating object passes a surrounding area of the magnetic fielddetector and wherein the position determining unit is adapted todetermine a position of a reciprocating object based on the detectedmagnetic signal.
 41. The concrete processing apparatus according toclaim 40, further comprising: a control unit controlling a reciprocationof the reciprocating shaft based on a position of the reciprocatingshaft which is provided to the control unit by the position sensordevice.
 42. The concrete processing apparatus according to claim 40,further comprising: a vehicle on which the concrete processing chamber,the reciprocating shaft and the position sensor device are mounted. 43.The concrete processing apparatus according to claim 40, furthercomprising: a further reciprocating shaft arranged in the concreteprocessing chamber adapted to reciprocate to mix concrete; wherein thereciprocating shaft and the further reciprocating shaft are operable ina countercyclical manner.
 44. A method for determining a position of areciprocating object, comprising: detecting a signal by a magnetic fielddetector, the signal being generated by a magnetically encoded regionfixed on a reciprocating object when the magnetically encoded regionreciprocating with the reciprocating object passes a surrounding area ofthe magnetic field detector; and determining a position of areciprocating object based on the detected signal.